Liquid crystal display device having electrode units each provided with a solid part and an extending part and method of manufacturing the same

ABSTRACT

The invention relates to a liquid crystal display device used as a display part of an information equipment and a method of manufacturing the same, and has an object to provide the liquid crystal display device which can obtain excellent display characteristics without raising the manufacture cost and the method of manufacturing the same. The liquid crystal display device includes a pair of substrates disposed to be opposite to each other, a liquid crystal sealed between the pair of substrates and aligned almost vertically to the substrate when a voltage is not applied, a pair of quarter-wave plates respectively disposed at outer sides of the pair of substrates, a pair of polarizing plates respectively disposed at outer sides of the pair of quarter-wave plates, and a pixel area including a reflection area provided with a reflecting plate having an almost flat reflecting surface and for reflecting light incident from one of the substrates, and a transmission area for causing light incident from the other of the substrates to be transmitted toward the one of the pair of substrates.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a liquid crystal display device used asa display part of an information equipment or the like and a method ofmanufacturing the same, and particularly to a transreflective typeliquid crystal display device used for a low power consumption equipmentsuch as a portable information terminal and a method of manufacturingthe same.

2. Description of the Related Art

In recent years, an active matrix type liquid crystal display deviceincluding a thin film transistor (TFT) in each pixel has been widelyused as a display device for any use. The liquid crystal display deviceis classified into a transmission type, a reflection type and atransreflective type by its lighting system. In the transmission type,transmitted light from a backlight unit is used for display. In thereflection type, reflected light of outside light is used for display.In the transreflective type, transmitted light of a backlight unit isused for display in a dark place and reflected light of outside light isused for display in a bright place. In recent years, as a display devicefor a mobile terminal or a notebook PC, a transreflective type(reflective and transmissive) liquid crystal display device in whichdisplay in both reflective and transmissive modes is enabled has beenused.

Here, a conventional liquid crystal display device will be described.FIG. 74 shows a sectional structure of a reflection type liquid crystaldisplay device disclosed in non-patent document 1 (set forth below). Asshown in FIG. 74, a liquid crystal 106 is sealed between a pair ofsubstrates 102 and 104 disposed to be opposite to each other. Thealignment state of the liquid crystal 106 is a bend alignment calledROCB (Reflective Optically Compensated Birefringence). A reflectingelectrode 116 having a mirror-like flat reflecting surface is formed onthe surface of the one substrate 102 at the side of the liquid crystal106. A common electrode 142 made of a transparent electrode film isformed on the surface of the other substrate 104 at the side of theliquid crystal 106. A phase difference film (quarter-wave plate) 120, apolarizing plate 122 and an optical path control film 124 are disposedin this order at the panel outer side (observer side) of the othersubstrate 104.

The optical path of incident outside light is bent by the optical pathcontrol film 124, reaches the reflecting electrode 116, is reflected,and is emitted toward the observer side. Since the optical path controlfilm 124 for diffusing and transmitting light is provided, the opticalpath of the light reflected at the surface of the optical path controlfilm 124 is different from the optical path of the light having beentransmitted through the optical path control film 124 and reflected atthe surface of the reflecting electrode 116. Then, when the observersees the display screen, the display and the outside light do notoverlap with each other, and a clear display image can be observed.

FIGS. 75A and 75B show a structure of a transreflective type liquidcrystal display device disclosed in non-patent document 2 (set forthbelow). FIG. 75A shows a structure of approximately one pixel of thetransreflective type liquid crystal display device, and FIG. 75B shows asectional structure of the transreflective type liquid crystal displaydevice cut along line X—X of FIG. 75A. As shown in FIGS. 75A and 75B, apixel area is divided into a transmission area T and a reflection areaR. An insulating material (resin layer) 130 is formed in the reflectionarea R of a TFT substrate 102 so that the cell thickness of thereflection area R becomes half of that of the transmission area T. Areflecting electrode 116 having an uneven surface is formed on theinsulator 130. A protrusion 132 for alignment controlling a verticallyaligned liquid crystal 106 is formed at the center part of thetransmission area T of an opposite substrate 104. A pair of quarter-waveplates 120 are respectively disposed at the panel outer side of the TFTsubstrate 102 and at the panel outer side of the opposite substrate 104.A pair of polarizing plates 122 are respectively disposed at the furtherouter sides of the respective quarter-wave plates 120.

Although this liquid crystal display device is the same as the liquidcrystal display device shown in FIG. 74 in that the reflecting electrode116 is formed on the surface of the substrate 102 at the side of theliquid crystal 106, the reflecting surface of the reflecting electrode116 is uneven. The incident outside light from the observer side isscattered and reflected at the reflecting electrode 116, and is emittedtoward the observer side.

FIG. 76A shows a state in which a voltage is not applied to the liquidcrystal 106, and FIG. 76B shows a state where a predetermined voltage isapplied to the liquid crystal 106. As shown in FIG. 76A, in the state ofvoltage non-application, since a liquid crystal molecule is alignedvertically to the substrate surface, the liquid crystal 106 does notexert an optical effect on light. When a reflective display isperformed, the light having been transmitted through the polarizingplate 122 is transmitted through the quarter-wave plate 120 and isincident on the liquid crystal 106, and after the light is reflected atthe reflecting electrode 116, it is again transmitted through thequarter-wave plate 120. That is, the light is transmitted through thequarter-wave plate 120 twice, so that its polarization state is rotatedby 90°. Accordingly, this light is absorbed by the polarizing plate 122.Thus, black is displayed in the reflection mode.

Besides, when a transmissive display is performed, light having beentransmitted through the polarizing plate 122 at the side of a backlightunit 188 is transmitted through the quarter-wave plate 120, is incidenton the liquid crystal 106, and is transmitted through the quarter-waveplate 120 at the observer side. That is, the light is transmittedthrough the quarter-wave plate 120 twice, so that its polarization stateis rotated by 90°. Accordingly, this light is absorbed by the polarizingplate 122 at the observer side. Thus, black is displayed in thetransmission mode.

On the other hand, in the state where the predetermined voltage isapplied, since the liquid crystal molecule is inclined with respect tothe substrate surface, the liquid crystal 106 exerts a predeterminedoptical effect on light. As shown in FIG. 76B, light having beentransmitted through the polarizing plate 122 changes its polarizationstate by the liquid crystal 106. Thus, white is displayed in both thereflection and transmission modes.

-   [Patent Document 1] JP-A-2000-56326-   [Patent Document 2] JP-A-2000-171789-   [Patent Document 3] JP-A-2002-202511-   [Patent Document 4] JP-A-6-175126-   [Patent Document 5] JP-A-7-311383-   [Patent Document 6] JP-A-11-281972-   [Patent Document 7] JP-A-2000-47251-   [Non-patent Document 1] Uchida et al. “A Bright Reflective LCD Using    Optically Compensated Birefringence Cell with Gray-Scale Capability    and Fast Response”, SID 96 DIGEST, p. 618–621-   [Non-patent Document 2] Jisaki et al. “Development of Transflective    LCD for High Contrast and Wide Viewing angle by Using Homeotropic    Alignment”, Asia Display/IDW '01, p. 133

In the structure of the reflection type liquid crystal display device asshown in FIG. 74, a use in combination with the transmission type hasnot been realized. This is because in the reflection type, on thepremise that the light is transmitted through the liquid crystal 106twice, the alignment state of the liquid crystal 106 is a hybridalignment. In the hybrid alignment, there is a problem thatbirefringence is small when it is used in the transmission type, and asufficient white display can not be performed. Besides, when it is usedin the transmission type, there is a problem that viewing anglecharacteristics are low.

On the other hand, in the transreflective type liquid crystal displaydevice shown in FIGS. 75A to 76B, it is proposed that the surface of thereflecting electrode 116 is formed to be uneven. However, in order tomanufacture the transreflective type liquid crystal display devicehaving the uneven reflecting electrode 116, in addition to a manufactureprocess of a normal transmission type liquid crystal display device, aprocess, such as formation and patterning of a resin layer and formationof the reflecting electrode 116, is further required. Thus, there arisesa problem that the manufacture cost of the liquid crystal display deviceis raised.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a liquid crystaldisplay device which can obtain excellent display characteristicswithout raising the manufacture cost and a method of manufacturing thesame.

The above object is achieved by a liquid crystal display deviceincluding a pair of substrates disposed to be opposite to each other, aliquid crystal sealed between the pair of substrates and aligned almostvertically to the substrate when a voltage is not applied, a pair ofquarter-wave plates respectively disposed at outer sides of the pair ofsubstrates, a pair of polarizing plates respectively disposed at outersides of the pair of quarter-wave plates, and a pixel area including areflection area provided with a reflecting plate having an almost flatreflecting surface and for reflecting light incident from one of thepair of substrates, and a transmission area for causing light incidentfrom the other of the pair of substrates to be transmitted toward theone of the pair of substrates.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 1B are views showing a basic structure of a liquid crystaldisplay device according to a first embodiment of the invention;

FIG. 2 is a view showing a schematic structure of a liquid crystaldisplay device according to example 1-1 of the first embodiment of theinvention;

FIG. 3 is a view schematically showing an equivalent circuit of theliquid crystal display device according to the example 1-1 of the firstembodiment of the invention;

FIG. 4 is a view showing the structure of the liquid crystal displaydevice according to the example 1-1 of the first embodiment of theinvention;

FIG. 5 is a view showing a structure of a conventional liquid crystaldisplay device;

FIG. 6 is a view showing a modified example of the structure of theliquid crystal display device according to the example 1-1 of the firstembodiment of the invention;

FIG. 7 is a view showing a structure of a liquid crystal display deviceaccording to example 1-2 of the first embodiment of the invention;

FIG. 8 is a view showing a structure of a conventional liquid crystaldisplay device;

FIG. 9 is a view showing an arrangement of a polarizing plate and thelike of the liquid crystal display device according to the example 1-2of the first embodiment of the invention;

FIG. 10 is a block diagram showing a driving method of a liquid crystaldisplay device according to example 1-3 of the first embodiment of theinvention;

FIG. 11 is a view showing a structure of a liquid crystal display deviceaccording to example 1-4 of the first embodiment of the invention;

FIG. 12 is a view showing a modified example of the structure of theliquid crystal display device according to the example 1-4 of the firstembodiment of the invention;

FIG. 13 is a sectional view showing a structure of a liquid crystaldisplay device as the premise of a second embodiment of the invention;

FIG. 14 is a sectional view showing a structure of the liquid crystaldisplay device as the premise of the second embodiment of the invention;

FIG. 15 is a sectional view showing a structure of a liquid crystaldisplay device according to the second embodiment of the invention;

FIG. 16 is a sectional view showing a structure of the liquid crystaldisplay device according to the second embodiment of the invention;

FIG. 17 is a sectional view showing a structure of the liquid crystaldisplay device according to the second embodiment of the invention;

FIG. 18 is a sectional view showing a structure of the liquid crystaldisplay device according to the second embodiment of the invention;

FIG. 19 is a sectional view showing a structure of the liquid crystaldisplay device according to the second embodiment of the invention;

FIG. 20 is a sectional view showing a structure of the liquid crystaldisplay device according to the second embodiment of the invention;

FIG. 21 is a sectional view showing a structure of the liquid crystaldisplay device according to the second embodiment of the invention;

FIG. 22 is a sectional view showing a structure of the liquid crystaldisplay device according to the second embodiment of the invention;

FIG. 23 is a view for explaining the liquid crystal display deviceaccording to the second embodiment of the invention;

FIG. 24 is a view for explaining the liquid crystal display deviceaccording to the second embodiment of the invention;

FIG. 25 is a view showing an arrangement of a reflecting protrusion of aliquid crystal display device according to example 2-1 of the secondembodiment of the invention;

FIG. 26 is a photograph showing a structure of the liquid crystaldisplay device according to the example 2-1 of the second embodiment ofthe invention;

FIG. 27 is an alignment photograph when white is displayed in areflection mode;

FIG. 28 is an alignment photograph when white is displayed in atransmission mode;

FIG. 29 is a graph showing a result of measurement of reflectioncharacteristics of the liquid crystal display device according to theexample 2-1 of the second embodiment of the invention;

FIG. 30 is a graph showing a result of measurement of reflectioncharacteristics of the liquid crystal display device according to theexample 2-1 of the second embodiment of the invention;

FIG. 31 is a graph showing a result of measurement of transmissioncharacteristics of the liquid crystal display device according to theexample 2-1 of the second embodiment of the invention;

FIG. 32 is a plan view showing a structure of one pixel of aconventional liquid crystal display device;

FIG. 33 is a plan view showing a structure of one pixel of a liquidcrystal display device according to a third embodiment of the invention;

FIG. 34 is a sectional view showing a structure of the liquid crystaldisplay device according to the third embodiment of the invention;

FIG. 35 is a view showing an arrangement of a polarizing plate and thelike of the liquid crystal display device according to the thirdembodiment of the invention;

FIG. 36 is a plan view showing a structure of one pixel in a case wherean electrode unit is made of only comb electrodes;

FIG. 37 is a graph of measurement of a rate of change in brightness withrespect to a variation in width of an extension part of a combelectrode;

FIGS. 38A to 38D are process sectional views (No. 1) showing a method ofmanufacturing the liquid crystal display device according to the thirdembodiment of the invention;

FIGS. 39A to 39C are process sectional views (No. 2) showing the methodof manufacturing the liquid crystal display device according to thethird embodiment of the invention;

FIGS. 40A to 40C are process sectional views (No. 3) showing the methodof manufacturing the liquid crystal display device according to thethird embodiment of the invention;

FIGS. 41A to 41N are plan views showing shapes of electrode units of aliquid crystal display device according to a modified example of thethird embodiment of the invention;

FIG. 42 is a plan view showing a structure of one pixel of a liquidcrystal display device according to a fourth embodiment of theinvention;

FIG. 43 is a plan view showing a structure of one pixel of a liquidcrystal display device according to a fifth embodiment of the invention;

FIGS. 44A to 44C are plan views showing shapes of electrode units of aliquid crystal display device according to a modified example of thefifth embodiment of the invention;

FIG. 45 is a plan view showing a structure of one pixel of a liquidcrystal display device according to a sixth embodiment of the invention;

FIG. 46 is a plan view showing a structure of one pixel of a liquidcrystal display device according to a seventh embodiment of theinvention;

FIG. 47 is a plan view showing a structure of one pixel of a liquidcrystal display device according to an eighth embodiment of theinvention;

FIGS. 48A and 48B are sectional views showing a structure of the liquidcrystal display device according to the eighth embodiment of theinvention;

FIG. 49 is a view showing an arrangement of a polarizing plate and thelike of the liquid crystal display device according to the eighthembodiment of the invention;

FIG. 50 is a plan view showing a structure of one pixel in a case wherethe number of reflecting electrode layers is changed in the liquidcrystal display device according to the eighth embodiment of theinvention;

FIG. 51 is a plan view showing a structure of one pixel in a case wherea reflecting electrode is formed in an area where a storage capacitorelectrode is formed in the liquid crystal display device according tothe eighth embodiment of the invention;

FIGS. 52A and 52B are graphs showing a relation between the areal ratioof a reflection area and the reflectivity in the liquid crystal displaydevice according to the eighth embodiment of the invention, and arelation between the areal ratio of the reflection area and thetransmissivity;

FIGS. 53A and 53B are graphs showing a relation between the areal ratioof a transmission area and the reflectivity in the liquid crystaldisplay device according to the eighth embodiment of the invention, anda relation between the areal ratio of the transmission area and thetransmissivity;

FIGS. 54A to 54D are process sectional views (No. 1) showing a method ofmanufacturing the liquid crystal display device according to the eighthembodiment of the invention;

FIGS. 55A to 55C are process sectional views (No. 2) showing the methodof manufacturing the liquid crystal display device according to theeighth embodiment of the invention;

FIG. 56 is a plan view showing a structure of one pixel of a liquidcrystal display device according to a ninth embodiment of the invention;

FIGS. 57A and 57B are plan views showing a structure of the liquidcrystal display device according to the ninth embodiment of theinvention;

FIG. 58 is a sectional view taken in a direction along a gate bus lineof a liquid crystal display device according to a tenth embodiment ofthe invention;

FIG. 59 is a sectional view taken in a direction along a gate bus lineof a liquid crystal display device according to a modified example ofthe tenth embodiment of the invention;

FIG. 60 is a sectional view taken in a direction along a gate bus lineof a liquid crystal display device according to an eleventh embodimentof the invention;

FIGS. 61A to 61C are process sectional views (No. 1) showing a method ofmanufacturing the liquid crystal display device according to theeleventh embodiment of the invention;

FIGS. 62A to 62C are process sectional views (No. 2) showing the methodof manufacturing the liquid crystal display device according to theeleventh embodiment of the invention;

FIGS. 63A to 63C are process sectional views (No. 3) showing the methodof manufacturing the liquid crystal display device according to theeleventh embodiment of the invention;

FIG. 64 is a sectional view taken in a direction along a gate bus lineof a liquid crystal display device according to a modified example ofthe eleventh embodiment of the invention;

FIG. 65 is a plan view showing a structure of one pixel of a liquidcrystal display device according to a twelfth embodiment of theinvention;

FIG. 66 is a sectional view showing a structure of the liquid crystaldisplay device according to the twelfth embodiment of the invention;

FIGS. 67A to 67D are process sectional views (No. 1) showing a method ofmanufacturing the liquid crystal display device according to the twelfthembodiment of the invention;

FIGS. 68A to 68C are process sectional views (No. 2) showing the methodof manufacturing the liquid crystal display device according to thetwelfth embodiment of the invention;

FIG. 69 is a plan view showing a structure of one pixel of a liquidcrystal display device according to a thirteenth embodiment of theinvention;

FIG. 70 is a sectional view showing a structure of the liquid crystaldisplay device according to the thirteenth embodiment of the invention;

FIG. 71 is a plan view showing a structure of one pixel of a liquidcrystal display device according to a fourteenth embodiment of theinvention;

FIG. 72 is a plan view showing a structure of the liquid crystal displaydevice according to the fourteenth embodiment of the invention;

FIGS. 73A and 73B are plan views showing other shapes of a branch partof an electrode unit in the liquid crystal display device of theinvention;

FIG. 74 is a sectional view showing a structure of a conventional liquidcrystal display device;

FIGS. 75A and 75B are views showing a structure of a conventional liquidcrystal display device; and

FIGS. 76A and 76B are sectional view showing a structure of theconventional liquid crystal display device.

DETAILED DESCRIPTION OF THE INVENTION FIRST EMBODIMENT

A liquid crystal display device according to a first embodiment of theinvention and a method of manufacturing the same will be described withreference to FIGS. 1A to 12. In this embodiment, excellent points of thetwo liquid crystal display devices already described as the related artare extracted and combined, and a method is devised to eliminate thenecessity of changing a manufacture process of a normal transmissiontype liquid crystal display device.

FIGS. 1A and 1B are sectional views schematically showing a basicstructure of a liquid crystal display device according to thisembodiment. FIG. 1A shows an optical path at the time of reflectivedisplay, and FIG. 1B shows an optical path at the time of transmissivedisplay. As shown in FIGS. 1A and 1B, a liquid crystal 6 is sealedbetween a TFT substrate 2 and an opposite substrate (CF substrate) 4,which are disposed to be opposite to each other. An alignment state ofthe liquid crystal 6 is a vertical alignment. The TFT substrate 2 isformed on a glass substrate 10, and includes a metal reflecting plate 54having an almost flat reflecting surface. As the reflecting plate 54, anelectrode such as, for example, a storage capacitor electrode is used.An insulating film 30 is formed on the reflecting plate 54. An almostflat and transparent pixel electrode 16 is formed on the insulating film30. The opposite substrate 4 includes a transparent common electrode 42formed on a glass substrate 11.

A quarter-wave plate 51, a polarizing plate 86 and an optical pathcontrol film (light scattering layer) 52 are disposed in this order atthe panel outer side (observer side) of the opposite electrode 4. Aquarter-wave plate 50 and a polarizing plate 87 are disposed in thisorder at the panel outer side of the TFT substrate 2. Polarizing axes ofboth the polarizing plates 86 and 87 are orthogonal to each other. Abacklight unit 88 is disposed at the further outer side of thepolarizing plate 87.

Since a liquid crystal molecule is aligned almost vertically to asubstrate surface in a voltage non-application state, the liquid crystal6 does not exert an optical effect on light. When a reflective displayis performed, incident outside light is reflected by the reflectingplate 54. Here, the light having been transmitted through the polarizingplate 86 is transmitted through the quarter-wave plate 51, and isincident on the liquid crystal 6, and after the light is reflected atthe reflecting electrode 16, it is again transmitted through thequarter-wave plate 51. That is, the light is transmitted through thequarter-wave plate 51 twice, so that its polarization state is rotatedby 90°. Accordingly, this light is absorbed by the polarizing plate 86.Thus, black is displayed in the reflection mode.

Besides, when a transmissive display is performed, light having beentransmitted through the polarizing plate 87 at the side of the backlightunit 88 is transmitted through the quarter-wave plate 50, is incident onthe liquid crystal 6, and is transmitted through the quarter-wave plate51. That is, the light is transmitted through the quarter-wave plates 50and 51 twice, so that its polarization state is rotated by 90°.Accordingly, this light is absorbed by the polarizing plate 86 at theobserver side. Thus, black is displayed in the transmission mode.

On the other hand, in a state where a predetermined voltage is applied,the liquid crystal molecule is inclined with respect to the substratesurface. Thus, birefringence as an optical effect occurs in the liquidcrystal 6, and a polarization state of transmitted light is changed.When the reflective display is performed, the incident outside light istransmitted through the liquid crystal 6, so that its polarization stateis changed, and the light is transmitted through the polarizing plate86. Thus, white or gray is displayed in the reflection mode. When thetransmissive display is performed, the incident light from the backlightunit 88 is also transmitted through the liquid crystal 6, so that itspolarization state is changed, and the light is transmitted through thepolarizing plate 86. Thus, white or gray is displayed in thetransmission mode.

In this embodiment, since an electrode such as a storage capacitorelectrode formed on the general TFT substrate 2 is used as thereflecting plate 54, there is no addition in the manufacture process.Here, in the transmission mode, the reflection of the outside light atthe reflecting plate 54 at the time when the backlight unit 88 is turnedon is not very annoying. This is because both the state where black isdisplayed in the transmission mode and the state where black isdisplayed in the reflection mode are the voltage non-application states,and when black is displayed in the transmission mode, there is noreflection of the outside light.

A film for scattering only incident light at an incident angle in apredetermined range is used as the optical path control film 52. Forexample, the incident light from the sun is scattered by the opticalpath control film 52 and is reflected by the reflecting plate 54. Thereflected light is used for the display and is emitted toward theobserver side. By this, for example, even in the case of the lightsource such as the sun, the display can be performed using the reflectedlight at the reflecting plate 54 while the surface reflection isavoided. Incidentally, it is desirable that when the reflected light isagain transmitted through the optical path control film 52, scatteringdoes not occur.

Hereinafter, a description will be given of specific examples.

EXAMPLE 1-1

A liquid crystal display device according to example 1-1 of thisembodiment will be described with reference to FIGS. 2 to 6. FIG. 2shows a schematic structure of the liquid crystal display deviceaccording to this example. As shown in FIG. 2, the liquid crystaldisplay device includes a TFT substrate 2 provided with gate bus linesand drain bus lines formed to intersect with each other through aninsulating film, and a TFT and a pixel electrode formed in each pixel.Besides, the liquid crystal display device includes an oppositeelectrode 4 in which a common electrode and a CF are formed, and aliquid crystal (not shown) sealed between both the substrates 2 and 4.

FIG. 3 schematically shows an equivalent circuit of an element formed onthe TFT substrate 2. A plurality of gate bus lines 12 extending in thehorizontal direction of the drawing are formed in parallel with eachother on the TFT substrate 2. A plurality of drain bus lines 14intersecting with the gate bus lines 12 through an insulating film andextending in the vertical direction of the drawing are formed inparallel with each other. Respective areas surrounded by the pluralityof gate bus lines 12 and the drain bus lines 14 become pixel areas. ATFT 20 and a pixel electrode 16 are formed in each of the pixel areasdisposed in a matrix form. A drain electrode of each TFT 20 is connectedto the adjacent drain bus line 14, a gate electrode is connected to theadjacent gate bus line 12, and a source electrode is connected to thepixel electrode 16. Storage capacitor bus lines 18 are formed inparallel with the gate bus lines at almost the centers of the respectivepixel areas.

Again, in FIG. 2, the TFT substrate 2 is provided with a gate bus linedriving circuit 80 in which a driver IC for driving the plurality ofgate bus lines is mounted and a drain bus line driving circuit 82 inwhich a driver IC for driving the plurality of drain bus lines ismounted. These driving circuits 80 and 82 output scanning signals anddata signals to predetermined gate bus lines or drain bus lines on thebasis of predetermined signals outputted from a control circuit 84. Apolarizing plate 87 is disposed on a substrate surface of the TFTsubstrate 2 at the opposite side to an element formation surface, and abacklight unit 88 is attached to a surface of the polarizing plate 87 atthe opposite side to the TFT substrate 2. On the other hand, apolarizing plate 86 disposed in crossed Nicols with respect to thepolarizing plate 87 is bonded to a surface of the opposite electrode 4at the opposite side to a common electrode formation surface.

FIG. 4 shows a structure of approximately one pixel of the liquidcrystal display device according to this example. As shown in FIG. 4,the plurality of gate bus lines 12 (two in FIG. 4) extending in thehorizontal direction of the drawing are formed almost in parallel witheach other on the TFT substrate 2 of the liquid crystal display device.The plurality of drain bus lines 14 (two in FIG. 4) extending in thevertical direction of the drawing are formed almost in parallel witheach other to intersect with the gate bus lines 12 through a not-showninsulating film. The TFT 20 is formed in the vicinity of each ofintersecting positions of the gate bus lines 12 and the drain bus lines14. An area surrounded by the gate bus line 12 and the drain bus line 14is a pixel area. The storage capacitor bus line 18 extending almost inparallel with the gate bus line 12 is formed to cross almost the centerof the pixel area. A storage capacitor electrode 19 is formed on thestorage capacitor bus line 18 in each pixel area.

The pixel electrode 16 made of a transparent conductive film of, forexample, ITO (Indium Tin Oxide) film is formed in the pixel area. Thepixel electrode 16 includes a plurality of electrode units 60 eachhaving a rectangular outer periphery and smaller than the pixel area, anelectrode blank part (slit) 62 formed between the adjacent electrodeunits 60, and a connection electrode 64 for electrically connectingelectrode units 60, which are separated by the slit 62, to each other.In the structure shown in FIG. 4, twelve electrode units 60 each havingan almost square outer periphery are formed in one pixel. A plurality ofspaces 66 cut from the respective end sides almost in parallel with thegate bus line 12 or the drain bus line 14 are formed at the outerperiphery of the electrode unit 60. On the other hand, a BM 68 forshading areas other than the pixel area is formed on the oppositeelectrode.

FIG. 5 shows a structure of a conventional liquid crystal display devicefor comparison with this example. Differently from the conventionalliquid crystal display device shown in FIG. 5, the liquid crystaldisplay device of this example is characterized in that a BM 68′ on astorage capacitor electrode 19 made of the same formation material as asource/drain electrode of a TFT 20 (or a storage capacitor bus line 18made of the same formation material as a gate electrode of the TFT 20)is not formed. In the conventional structure, although the BM 68′ isprovided to prevent the outside light from being reflected by thestorage capacitor electrode 19 (or the storage capacitor bus line 18),in this example, the storage capacitor electrode 19 (or the storagecapacitor bus line 18) is used as the reflecting plate.

FIG. 6 shows a modified example of the structure of the liquid crystaldisplay device according to this example. As shown in FIG. 6, in thismodified example, the storage capacitor electrode 19 (or the storagecapacitor bus line 18) is used as the reflecting plate, and further,circular reflecting plates 54 are separately provided in the pixel area.Each of the reflecting plates 54 is formed of the same formationmaterial as the gate electrode or the source/drain electrode of the TFT20, and is disposed to overlap with almost the center of the electrodeunit 60 when viewed in the direction vertical to the substrate surface.Besides, the reflecting plate 54 is electrically in a float state.Although not shown, LUMISTY (trademark) of Sumitomo Chemical Co., Ltd.is used as the optical path control film 52.

EXAMPLE 1-2

Next, a liquid crystal display device according to example 1-2 of thisembodiment will be described with reference to FIGS. 7 to 9. FIG. 7shows a structure of approximately one pixel of the liquid crystaldisplay device according to this example. FIG. 8 shows a structure of aconventional liquid crystal display device for comparison with thisexample. Differently from the conventional liquid crystal displaydevice, in this example, a BM 68′ on a storage capacitor electrode 19made of the same formation material as a source/drain electrode of a TFT20 is not formed. Besides, in this example, a protrusion 70 foralignment control is provided at the opposite electrode side. Theprotrusion 70 is disposed almost at the center of an electrode unit 60.Besides, the protrusion 70 on the storage capacitor electrode 19 isformed to be cross-shaped. By this, alignment division of liquid crystalis performed on the storage capacitor electrode 19 used as thereflecting plate, and the reflective display excellent in viewing anglecharacteristics can be realized.

FIG. 9 shows an arrangement of a polarizing plate and the like of theliquid crystal display device according to this example. As shown inFIG. 9, a polarizing plate (for example, SEG 1425, AG 150) 86 and apolarizing plate (for example, SEG 1425) 87, which are disposed incrossed Nicols, are disposed at both sides of a liquid crystal layer 6.A quarter-wave plate 51 is disposed between the liquid crystal layer 6and the polarizing plate 86. Besides, a quarter-wave plate 50 isdisposed between the liquid crystal layer 6 and the polarizing plate 87.For example, an ARTON film having an in-plane phase difference of 140 nmis used for each of the quarter-wave plates 50 and 51. A TAC film 72having a negative phase difference is disposed between the liquidcrystal layer 6 and the quarter-wave plate 51 in order to improveviewing angle characteristics. Besides, an optical film 74 of PCF 350 orthe like is disposed at the outer side of the polarizing plate 87.Incidentally, an upper part in the drawing is the observer side, and alower part in the drawing is the optical source side.

An angle between an optical axis (phase-lag axis) 91 of the quarter-waveplate 50 and an absorption axis 90 of the polarizing plate 87 isapproximately 45°. That is, when light emitted from a light source istransmitted through the polarizing plate 87 and the quarter-wave plate50 in this order, it becomes a circularly polarized light. Besides, anangle between an optical axis 94 of the quarter-wave plate 51 and anabsorption axis 95 of the polarizing plate 86 is approximately 45°. Theoptical axes 91 and 94 of both the quarter-wave plates 50 and 51 arealmost orthogonal to each other. In order to realize the symmetry ofviewing angles and to optimize viewing angle characteristics in thevertical and horizontal directions with respect to the display screen,the polarizing plates 86 and 87 and the quarter-wave plates 50 and 51are disposed as described below.

The absorption axis 90 of the polarizing plate 87 is disposed in thecounter clock wise direction of 150° with reference to the right part ofthe display screen. The optical axis 91 of the quarter-wave plate 50 isdisposed in the counterclockwise direction of 15° with reference to theright part of the display screen. The optical axis 94 of thequarter-wave plate 51 is disposed in the counterclockwise direction of105° with reference to the right part of the display screen. Theabsorption axis 95 of the polarizing plate 86 is disposed in thecounterclockwise direction of 60° with reference to the right part ofthe display screen.

EXAMPLE 1-3

Next, a liquid crystal display device according to example 1-3 of thisembodiment will be described with reference to FIG. 10. In the aboveexamples, the same voltage is applied in both the reflection type andthe transmission type. However, while light is transmitted only once inthe transmission area, light is transmitted twice in the reflection areato go and return. Thus, the optical effect in the reflection area istwice that in the transmission area, and for example, when white isdisplayed in the transmission area, the reflection area takes on a tingof yellow. In the transmission area, since the reflection area isconcealed by the storage capacitor electrode 19 and is not seen, thereis no problem. However, in the reflective display, the phenomenon oftaking on a tinge of yellow becomes a problem. Thus, in this example,when the reflective display is performed, the driving voltage islowered.

FIG. 10 is a block diagram showing a driving method of the liquidcrystal display device according to this example. With respect to achangeover between the transmission type and the reflection type, thereis a case where it is performed by the user and a case where it isperformed in synchronization with ON/OFF of the backlight unit, and FIG.10 shows both the cases. In the case where the liquid crystal displaydevice is used as the transmission type, a maximum driving voltage ismade, for example, 5 V equal to a normal driving voltage, and in thecase where it is used as the reflection type, the maximum drivingvoltage is made, for example, 3 V lower than the normal driving voltage.These driving voltages are selected so that when the same gradation isdisplayed, Δn in the reflection type becomes almost half of Δn in thetransmission type. Besides, when only the voltage adjustment isperformed, gradation characteristics become different between thetransmissive display and the reflective display. Thus, the relationbetween the gradation and the applied voltage is suitably adjusted, sothat the gradation characteristics become the same between thetransmissive display and the reflective display.

EXAMPLE 1-4

Next, a liquid crystal display device according to example 1-4 of thisembodiment and a method of manufacturing the same will be described withreference to FIG. 11 and FIG. 12. FIG. 11 shows a structure of a part ofa pixel of the liquid crystal display device according to this example.As shown in FIG. 11, an opening part (contact hole) 76 in which aprotective film (not shown) is opened is formed in most of the portionon a storage capacitor electrode 19 made of a lamination film in whichfilms of aluminum (Al) and titanium (Ti) are grown in this order. In theopening part 76, the Ti layer of the upper layer of the storagecapacitor electrode 19 is also removed by etching, and the surface ofthe Al layer of the lower layer is exposed as the reflecting surface.Besides, an electrode unit 60 (pixel electrode 16 or a connectionelectrode 64 in FIG. 11) formed on the protective film is electricallyconnected to the storage capacitor electrode 19 through the opening part76.

The storage capacitor electrode 19 and the opening part 76 are formed asdescribed below. An Al layer and a Ti layer are grown in this order onan insulating film formed on the whole surface on gate bus lines andstorage capacitor bus lines, and a lamination film is formed. Next, thelamination film is patterned into a specified shape, and the storagecapacitor electrode 19 is formed. Next, a protective film as aninsulating layer is formed on the storage capacitor electrode 19 and onthe whole substrate surface. Next, the protective film on the storagecapacitor electrode 19 is removed to form the opening part 76, andsubsequently, the Ti layer exposed through the opening part 76 isremoved by etching. By this, the Al layer of the storage capacitorelectrode 19 is exposed. Thereafter, a film of ITO is grown and ispatterned, so that the pixel electrode 16 or the connection electrode 64in FIG. 11 is formed so as to cover, for example, the exposed Al layer.

According to this example, the surface of the Al layer is exposed inmost of the storage capacitor electrode 19 functioning as the reflectingplate. The reflectivity of Al is remarkably high as compared with Ti.Thus, the high reflectivity of Al can be used, and high displaycharacteristics can be obtained at the time of the reflective display.

Next, a modified example of the structure of the liquid crystal displaydevice according to this example will be described. In the structure asshown in FIG. 11, the ITO layer and the Al layer are in direct contactwith each other. Thus, there arises a problem that there is a fear thatcorrosion due to a cell effect occurs. FIG. 12 shows the structure ofthe liquid crystal display device according to this modified example inwhich this problem does not arise. As shown in FIG. 12, in this modifiedexample, when viewed in the direction vertical to the substrate surface,a reflecting plate 54 is formed which does not overlap with an electrodeunit 60 made of ITO and a connection electrode 64. The reflecting plate54 is formed of the same formation material as the gate electrode of theTFT 20 or the same formation material as the source/drain electrode.Besides, the reflecting plate 54 is electrically in a float state. Thereflecting plate 54 is formed in such a manner that for example, afterthe lamination film of the Al layer and the Ti layer is patterned, theTi layer of the upper layer is removed in a process for forming thecontact hole on the source electrode of the TFT 20 or on the storagecapacitor electrode 19. Accordingly, the reflecting surface of thereflecting plate 54 is formed of the Al layer. In this modified example,it is possible to prevent the ITO layer and the Al layer from reactingwith each other. The liquid crystal on the reflecting plate 54 is drivenby an oblique electric field from the electrode unit 60.

As described above, according to this embodiment, the transreflectivetype liquid crystal display device which can perform the display in boththe transmission and reflection modes can be manufactured by usingalmost the same manufacture process as the transmission type liquidcrystal display device. By this, the inexpensive transreflective typeliquid crystal display device can be realized without raising themanufacture cost.

SECOND EMBODIMENT

Next, a liquid crystal display device according to a second embodimentof the invention will be described with reference to FIGS. 13 to 31. Atransreflective type (reflective and transmissive type) liquid crystaldisplay device performs a reflective display using outside light in abright place, and performs a transmissive display using a backlight unitin a dark place. In the reflection type liquid crystal display device,the display is hard to see in the dark place, and in the transmissiontype liquid crystal display device, the display is hard to see in thebright place. In the transreflective type liquid crystal display device,since an easily viewable display can be selected in places different inbrightness, it is widely used for a portable information terminal andthe like.

In the reflection type liquid crystal display device, when a reflectingfilm (reflecting electrode) is made to have a flat mirror surface, adisplay becomes bright in a regular reflection area, and a displaybecomes dark in other areas. Thus, the dependency on viewing angles ishigh and the display comes to have a metallic luster. Then, there isknown a technique in which unevenness having dot-like plane shape isformed on the surface of the reflecting film, so that reflected light isdiffused, and a display having no metallic luster is realized (forexample, see patent document 4). In the above reflection type liquidcrystal display device, since the reflecting surfaces are directed inrandom directions, in the case where light is incident from alldirections, it is reflected to the observer side at high efficiency, anda bright display can be obtained. However, in the case where light isincident from a specified direction as in an indoor place, there arisesa problem that the use efficiency of light is low, and the displaybecomes dark.

In the transmission type liquid crystal display device, there is known atechnique in which an alignment controlling inclination part is formedon at least one of transparent electrodes by partially upraising orcaving a contact surface with a liquid crystal layer, and the alignmentof the liquid crystal is controlled by the alignment controllinginclination part (for example, see patent document 5). In the abovetransmission type liquid crystal display device, as shown in FIGS. 13and 14, since the alignment direction (indicated by an arrow A) of aliquid crystal molecule 8 by an alignment controlling inclination part78 and the alignment direction (indicated by an arrow B) of a liquidcrystal molecule 8 by an electric field distortion become opposite toeach other, there arises a problem that the alignment of the liquidcrystal 6 does not become stable, poor alignment occurs, and thetransmissivity is lowered.

In the transreflective type liquid crystal display device, there isknown a technique in which a reflection part and a transmission part aredivided and are constructed in one pixel, and the electrode surface ofthe reflection part is formed into a continuous corrugate shape (forexample, see patent document 6). In the above transreflective typeliquid crystal display device, in addition to the problem arising in theforegoing reflection type liquid crystal display device, there arises aproblem that since the alignment direction of the liquid crystal can notbe divided in a pixel, viewing angle characteristics especially in thetransmission part are lowered.

An object of this embodiment is to provide a liquid crystal displaydevice which can obtain excellent display characteristics in both thetransmission and reflection modes.

This embodiment is characterized in that in a transreflective typeliquid crystal display device, a linear protrusion (protrusion columnwhose plane shape is constituted by straight lines) as an alignmentcontrolling structure is provided on a transparent electrode of onesubstrate, and a reflecting film is selectively formed on a surfaceincluding an inclined surface of the linear protrusion. Here, as long asthe plane shape is formed of the straight lines, the alignmentcontrolling structure may be a frame-like protrusion, not the linearprotrusion (the same applies to a hollow described below). When thevertical alignment is selected as the alignment state of liquid crystal,there does not occur such a state that a liquid crystal anchored on asubstrate interface at the time of black display is not switched andremains. Thus, a contrast ratio becomes high, and an easily viewabledisplay can be realized. Besides, a linear protrusion is provided on atransparent electrode of a substrate at a backlight unit side and areflecting film is selectively formed on the linear protrusion surface,so that light incident from a front direction and an oblique directioncan be efficiently reflected toward the observer side by using theinclined surface of the linear protrusion. Further, loss oftransmissivity can be suppressed to the minimum by causing an area abovethe linear protrusion to become a reflection area. Besides, since thethickness of the liquid crystal layer is different between thereflection area and the transmission area, it becomes possible to matchgradation characteristics of the reflective display and the transmissivedisplay.

Besides, this embodiment is characterized in that a hollow linearlyextending on one substrate is provided, and a reflecting film isselectively formed on a surface including an inclined surface of thehollow. That is, the alignment direction of the liquid crystal iscontrolled by the hollow instead of the linear protrusion. Although thesectional shape and the thickness of the liquid crystal layer in thereflection area become opposite to those in the case of the linearprotrusion, a similar effect to the linear protrusion can be expected.

Further, this embodiment is characterized in that a linear protrusion isprovided on a transparent electrode of one substrate, and a reflectingfilm is selectively formed as an under layer of the linear protrusion.FIG. 15 is a sectional view of a liquid crystal display device havingthe above structure. As shown in FIG. 15, a reflecting film 56 is formedas an under layer of a linear protrusion 70. Since the linear protrusion70 acts as a dielectric, an alignment direction (indicated by an arrowA) of a liquid crystal molecule 8 by an inclined surface of the linearprotrusion 70 is coincident with an alignment direction of a liquidcrystal molecule 8 by an electric field distortion, and the alignment ofthe liquid crystal 6 becomes more stable.

Further, this embodiment is characterized in that an alignmentcontrolling structure such as a linear protrusion or a hollow is formedto extend in a direction inclined by 45° with respect to an end side ofa pixel electrode, a direction substantially parallel thereto or adirection substantially orthogonal thereto. By this, light incident fromthese directions can be efficiently reflected toward the observer side.

Besides, this embodiment is characterized in that a reflecting film anda transparent electrode are electrically separated from each other. Forexample, when a voltage is enabled to be applied to only the reflectingfilm at the time of reflective display, and a voltage is enabled to beapplied to only the transparent electrode at the time of transmissivedisplay, an oblique electric field can be generated at a boundary partbetween a transmission area T and a reflection area R, and the alignmentdirection of the liquid crystal can be uniformly made the directionorthogonal to the boundary part. Besides, the reflecting film and thetransparent electrode different in ionization tendency can be insulatedfrom each other, and deterioration due to electrical corrosion can alsobe prevented.

FIGS. 16 and 17 are sectional views of liquid crystal display deviceshaving the above structure. FIG. 16 shows a state where a voltage isapplied to a pixel electrode 16, and a voltage is not applied to areflecting film 56 on a linear protrusion 70. FIG. 17 shows a statewhere a voltage is applied to a reflecting film 56 on a hollow 71 and avoltage is not applied to a pixel electrode 16. As shown in FIGS. 16 and17, the alignment direction (indicated by an arrow A) of a liquidcrystal molecule 8 by the inclined surface of the linear protrusion 70or the hollow 71 is coincident with the alignment direction (indicatedby an arrow B) of a liquid crystal molecule 8 by electric fielddistortion, and the alignment of the liquid crystal 6 becomes morestable.

Further, this embodiment is characterized in that a range of an averageinclination angle of an inclined surface of the alignment controllingstructure with respect to the substrate surface is made not less thanapproximately 0° and less than 20°. FIG. 18 shows a relation betweenlight outgoing in the front direction and an average inclination angle θof an inclined surface of the reflecting film 56. Although the lightreflected in the front direction by the inclined surface of thereflecting film 56 is incident in an oblique direction, the incidentangle depends on the inclination angle of the inclined surface. Therefractive index of a member constituting the transreflective typeliquid crystal display device is approximately 1.5, and the maximumincident angle θc of the light incident on the reflecting film 56becomes approximately 40° by Snell's law. Since the incident light ismirror reflected at the reflecting film 56, in order to reflect thelight incident at an incident angle of from 0° to 40° toward the frontdirection, it is necessary that the inclination angle of the inclinedsurface is not less than 0° and less than 20°. However, since theinclination angle of the inclined surface is continuously changed, whenthe average inclination angle indicating the average value of theinclination angle distribution is in this range, obliquely incidentlight can be efficiently reflected in the front direction.

Further, this embodiment is characterized in that another alignmentcontrolling structure (third alignment controlling structure) is formedin a gap part of alignment controlling structures extending in parallelwith each other on one substrate. FIG. 19 is a sectional view of aliquid crystal display device having the above structure. As shown inFIG. 19, when a reflecting film 56 is electrically connected to a pixelelectrode 16, the reflecting film 56 and the linear protrusion 70function as a conductive protrusion. In this case, as described above,since the alignment direction of the liquid crystal molecule 8 by theinclined surface and the alignment direction of the liquid crystalmolecule 8 by the electric field distortion become opposite to eachother, the alignment of the liquid crystal 6 does not become stable, andpoor alignment occurs. Then, a slit 62 is formed in the gap part betweenthe adjacent linear protrusions 70. By this, an alignment controllingforce is made to exert in the substrate plane direction, and the liquidcrystal alignment on the reflecting film 56 and the linear protrusion 70is aligned in the direction due to the electric field distortion.Incidentally, the alignment controlling structure in which thereflecting film 56 is not formed on the upper layer functions as adielectric. Thus, the alignment direction of the liquid crystal molecule8 by the inclined surface is coincident with the alignment direction ofthe liquid crystal molecule 8 by the electric field distortion, and thealignment of the liquid crystal 6 becomes stable.

Besides, this embodiment is characterized in that a slit obtained byremoving a part of a reflecting film on an alignment controllingstructure is formed. FIG. 20 is a sectional view of a liquid crystaldisplay device having the above structure. As shown in FIG. 20, areflecting film 56 on an almost flat surface of a linear protrusion 70is removed, and a slit 62 is formed. Further, this embodiment ischaracterized in that another alignment controlling structure (secondalignment controlling structure) is formed on the other substrate in anarea opposite to an alignment controlling structure through a liquidcrystal. FIG. 21 is a section view of a liquid crystal display devicehaving the above structure. As shown in FIG. 21, a slit 62 is formed onan opposite substrate 4 in an area opposite to a hollow 71. An alignmentcontrolling force is made to exert in a substrate vertical direction bythe slit 62, and liquid crystal alignment on the reflecting film 56 andthe linear protrusion 70, or on the reflecting film 56 and the hollow 71is made uniform in the direction due to the electric field distortion.By this, the alignment of the liquid crystal 6 becomes stable.

Further, this embodiment is characterized in that a linear protrusionhas a convex sectional shape, and is formed of a transparent materialhaving a refractive index larger than liquid crystal. FIG. 22 is apartial sectional view of a liquid crystal display device having theabove structure. As shown in FIG. 22, a reflecting film 56 is formed asan under layer of a linear protrusion 70. The linear protrusion 70 has aconvex (trapezoidal) sectional shape and is formed of a transparentresin having a refractive index larger than the liquid crystal 6.

FIG. 23 is a sectional view of a liquid crystal display device in whicha linear protrusion 70 has a rectangular sectional shape, and is formedof transparent resin having almost the same refractive index as theliquid crystal 6. FIG. 24 is a sectional view of a liquid crystaldisplay device in which a linear protrusion 70 has a rectangularsectional shape and is formed of transparent resin having a refractiveindex larger than the liquid crystal 6. As shown in FIGS. 23 and 24, inthe case where the sectional shape of the linear protrusion 70 isrectangular, irrespective of the refractive index of the formationmaterial, an incident angle θ1 and an outgoing angle θ2 become almostequal to each other, and mirror reflection is obtained. On the otherhand, as shown in FIG. 22, in the case where the linear protrusion 70has the convex sectional shape and is formed of transparent resin havingthe refractive index larger than the liquid crystal 6, an outgoing angleθ2 with respect to the reflecting film 56 becomes smaller than anincident angle θ1 with respect to the reflecting film 56. Accordingly,light incident from an oblique direction is reflected in the frontdirection.

Hereinafter, a description will be given of specific examples.

EXAMPLE 2-1

A liquid crystal display device according to example 2-1 of thisembodiment will be described with reference to FIGS. 25 to 31. FIG. 25shows an arrangement of a reflecting protrusion of the liquid crystaldisplay device according to this example. FIG. 26 is a photographshowing a structure of the liquid crystal display device according tothis example. As shown in FIGS. 25 and 26, a linear protrusion 70 and areflecting film 56 as its upper layer are formed as the reflectingprotrusion on a TFT substrate 2. The linear protrusion 70 is formed on apixel electrode 16 by using a resist (made by Shipley Far East Ltd.).The sectional shape of the linear protrusion 70 is convex, an averageinclination angle is 8°, and a peak height is 1.5 μm. The linearprotrusion 70 is formed almost in parallel with or inclined at an angleof 45° with respect to an end side of the pixel electrode 16. Thereflecting film 56 is selectively formed on the linear protrusion 70.The reflecting film 56 is electrically independently formed in eachpixel and is electrically connected to each pixel electrode 16. Besides,a slit 62 is formed in a gap part between the adjacent linearprotrusions 70. Both the linear protrusion 70 and the slit 62 are formedon the TFT substrate 2.

After the TFT substrate 2 and an opposite substrate 4 are formed, avertical alignment film (made of JSR Corporation) is applied to both thesubstrates 2 and 4. Thereafter, a spacer (made by Sekisui Fine ChemicalCo., Ltd.) with a bead diameter of 4.5 μm is scattered, and both thesubstrates 2 and 4 are bonded to each other to form a hollow panel. Aliquid crystal (made by MERCK JAPAN LTD) having a negative dielectricanisotropy is injected into the hollow panel, and a liquid crystaldisplay component is prepared. A right-handed circular polarizing plate(a polarizing plate and a quarter-wave plate) and a left-handedpolarizing plate are bonded to both surfaces of the liquid crystaldisplay component so that lag axes of quarter-wave plates are orthogonalto each other, and a transreflective type liquid crystal display deviceis fabricated. Alignment observation is made in both reflection andtransmission display modes. FIG. 27 is an alignment photograph whenwhite is display in the reflection mode, and FIG. 28 is an alignmentphotograph when white is displayed in the transmission mode. In therespective display modes, the occurrence of poor alignment is not seen.This is because the slit 62 is formed in the gap portion of the linearprotrusions 70, the alignment controlling force exerts in the directionparallel to the substrate, and the alignment direction is stabilized.

FIGS. 29 and 30 are graphs showing results of measurement of reflectioncharacteristics of the liquid crystal display device according to thisexample. FIG. 29 shows a change of reflectivity with respect to a changeof a direction angle. The horizontal axis indicates the direction angle,and the vertical axis indicates the reflectivity. A line A1 indicatesreflection characteristics of the liquid crystal display deviceaccording to this example, and a line A2 indicates reflectioncharacteristics of a conventional liquid crystal display device in whichan Al (aluminum) mirror reflecting film is formed. Light is incidentfrom a direction of a polar angle of 30°, and is received in a directionof a polar angle of 0°. FIG. 30 shows a change of reflectivity withrespect to a change of an incident angle (polar angle). The horizontalaxis indicates the incident angle and the inclination angle of acorresponding inclined surface, and the vertical axis indicates thereflectivity. A line B1 indicates reflection characteristics when lightis incident from a direction of a direction angle of 45° to the liquidcrystal display device according to this example, and a line B2indicates reflection characteristics when light is incident from adirection of a direction angle of 90° to the liquid crystal displaydevice according to this example. A line B3 indicates reflectioncharacteristics of the conventional liquid crystal display device inwhich the Al mirror reflecting film is formed.

As shown in FIG. 29, direction angle dependency occurs such that whenlight is incident from a direction of 45°, direction of 90° anddirection of 135°, the reflectivity becomes high. Besides, it has beenfound that as shown in FIG. 30, incident angle dependency occurs suchthat as the incident angle of light becomes small, the reflectivitybecomes high, and even at a considerably large incident angle, light of15 to 30% is reflected in the front direction. In this example, althoughthe reflecting film 56 and the linear protrusion 70 are formed almost inparallel with or at an angle of 45° with respect to the end side of thepixel electrode 16, when the reflecting film 56 and the linearprotrusion 70 are formed to be almost orthogonal to the end side of thepixel electrode 16, even if light is incident from a direction of 0° anda direction of 180°, the reflectivity can be made high.

FIG. 31 is a graph showing a result of measurement of transmissioncharacteristics of the liquid crystal display device according to thisexample. The horizontal axis indicates the voltage, and the verticalaxis indicates the transmissivity. A line C1 indicates transmissioncharacteristics of the transreflective type liquid crystal displaydevice according to this example, and a line C2 indicates transmissioncharacteristics of a conventional transmission type liquid crystaldisplay device in which the reflecting film 56 is not formed. Light isincident at a polar angle of 180°, and is received at a polar angle of0°. As shown in FIG. 31, in the liquid crystal display device accordingto this example, since the reflecting film 56 is formed on the linearprotrusion 70, as compared with the conventional transmission typeliquid crystal display device, the transmissivity is lowered by theamount of light transmitted through the linear protrusion 70. However,the rate of lowering of the transmissivity is slight in the vicinity ofa saturation voltage, and the transmission characteristics comparable tothe transmission type liquid crystal display device are obtained.Accordingly, according to this example, it is possible to realize thetransreflective type (minute reflection type) liquid crystal displaydevice which can perform a reflective display while the lowering oftransmission characteristics is suppressed.

EXAMPLE 2-2

Next, a liquid crystal display device according to example 2-2 of thisembodiment will be described. In this example, instead of a part of theprotrusion 70, a hollow 71 is formed, and a reflecting film 56 and apixel electrode 16 are electrically separated from each other. Besides,a slit 62 is formed on an opposite electrode 4 of an area opposite to agap portion between the adjacent protrusions 70 or hollows 71 through aliquid crystal 6. The liquid crystal display device similar to theexample 2-1 except for the above is fabricated. The hollow 71 is formedusing a resist so that a sectional shape is concave, an averageinclination angle is 8°, and a peak height difference becomes 1.5 μm.Besides, a reflecting film 56 is formed on the protrusion 70 and thehollow 71 in such a manner that the film is electrically separated fromthe pixel electrode 16. Alignment observation is performed in both thereflection and transmission display modes. As a result, in thetransmissive display in the vicinity of the protrusion 70, and inreflective display in the vicinity of the hollow 71, similarly to thealignment photographs shown in FIGS. 27 and 28, an alignment statewithout poor alignment is obtained. It has been confirmed that byelectrically separating the reflecting film 56 on the protrusion 70 andthe hollow 71 from the pixel electrode 16 and separately driving them,the alignment direction by the inclined surface of the protrusion 70 andthe hollow 71 is coincident with the alignment direction by electricfield distortion, and the alignment of the liquid crystal 6 becomesstable.

EXAMPLE 2-3

Next, a liquid crystal display device according to example 2-3 of thisembodiment will be described. In this example, a slit 62 is formed in areflecting film 56 on a protrusion 70. Besides, a slit 62 is formed onan opposite substrate 4 of an area opposite to a gap between theadjacent protrusions 70 through a liquid crystal 6, and a slit 62 is notformed on a TFT substrate 2 of a gap portion of the protrusions 70. Theliquid crystal display device similar to the example 2-1 except for theabove is fabricated. Alignment observation is performed in both thereflection and transmission display modes. As a result, in therespective display modes, similarly to the alignment photographs shownin FIGS. 27 and 28, an alignment state without poor alignment isobtained. It has been confirmed that since the slit 62 is formed in thereflecting film 56 on the protrusion 70, the alignment direction by theinclined surface of the protrusion 70 is coincident with the alignmentdirection by the electric field distortion, and the alignment of theliquid crystal 6 becomes stable.

EXAMPLE 2-4

Next, a liquid crystal display device according to example 2-4 of thisembodiment will be described. In this embodiment, except that areflecting film 56 on a hollow 71 is electrically connected to a pixelelectrode 16, the liquid crystal display device is fabricated similarlyto the example 2-2. Alignment observation is made in both the reflectionand transmission display modes. As a result, in the respective displaymodes, similarly to the alignment photographs shown in FIGS. 27 and 28,the alignment state without poor alignment is obtained. It has beenconfirmed that since the slit 62 is formed on the opposite electrode 4of the area opposite to the hollow 71 through the liquid crystal 6, thealignment direction by the inclined surface of the hollow 71 iscoincident with the alignment direction by the electric fielddistortion, and the alignment of the liquid crystal 6 becomes stable.

EXAMPLE 2-5

Next, a liquid crystal display device according to example 2-5 of thisembodiment will be described. In this example, a protrusion 70 having aconvex sectional shape is formed using a transparent resin (made by JSRCorporation) with a refractive index of 1.7 larger than the refractiveindex of liquid crystal, and a reflecting film 56 is selectively formedas an under layer of the protrusion 70. Besides, a slit 62 is formed onan opposite substrate 4 in an area opposite to a gap portion between theadjacent protrusions 70 through a liquid crystal 6, and a slit 62 is notformed on a TFT substrate 2 in the gap portion between the protrusions70. The liquid crystal display device similar to the example 2-1 exceptfor the above is fabricated. Alignment observation is made in both thereflection and transmission display modes. As a result, in therespective display modes, similarly to the alignment photographs shownin FIGS. 27 and 28, the alignment state without poor alignment isobtained. The reflecting film 56 is selectively formed as the underlayer of the protrusion 70, so that the protrusion 70 and the reflectingfilm 56 function as an insulating protrusion. Thus, it has beenconfirmed that the alignment direction by the inclined surface of theprotrusion 70 is coincident with the alignment direction by the electricfield distortion, and the alignment of the liquid crystal 6 becomesstable.

As described above, in the liquid crystal display device according tothis embodiment, the bright reflective display can be realized withlittle loss of transmissivity, and the transmissive display with a wideviewing angle range can be realized. By this, it is possible to realizethe liquid crystal display device having an easily viewable display inany places.

THIRD EMBODIMENT

Next, a liquid crystal display device according to a third embodiment ofthe invention will be described.

In a vertical alignment type liquid crystal display device, a liquidcrystal having a negative dielectric anisotropy is aligned in thevertical direction by using a vertical alignment film when no voltage isapplied, and is aligned to be inclined when a voltage is applied. In thevertical alignment type liquid crystal display device, since the liquidcrystal is aligned in the vertical direction when no voltage is applied,there are merits that black display quality is excellent, a display withhigh contrast is possible, a viewing angle is wide, and a response isquick.

In the vertical alignment type liquid crystal display device, as amethod of performing the alignment control of liquid crystal, a methodis proposed in which a plurality of electrode units each smaller thanone pixel are provided in one pixel, and these are made pixel electrodesto constitute the one pixel.

For example, patent document 7 discloses a method of forming a solidelectrode unit smaller than one pixel in the one pixel.

FIG. 32 is a plan view showing a structure of one pixel of a liquidcrystal display device disclosed in patent document 7. As shown in thedrawing, gate bus lines 12 extending in the horizontal direction in thedrawing are formed on a TFT substrate almost in parallel with each otherat predetermined intervals. Further, drain bus lines 14 almostvertically intersecting with the gate bus lines 12 through an insulatingfilm and extending in the vertical direction in the drawing are formedalmost in parallel with each other at predetermined intervals. Areassurrounded by the plurality of gate bus lines 12 and the drain bus lines14 are pixel areas. A storage capacitor bus line 18 extending almost inparallel with the gate bus line 12 is formed to intersect with almostthe center of each of the pixel areas. A storage capacitor electrode 19is formed on the storage capacitor bus line 18 through an insulatingfilm in each of the pixels.

A TFT 20 is formed in the vicinity of each of intersection positions ofthe gate bus lines 12 and the drain bus lines 14.

A pixel electrode 16 made of a transparent conductive film is formed inthe pixel area.

The pixel electrode 16 includes a plurality of square electrode units 60each smaller than the pixel area, electrode blank parts (slits) 62formed between the adjacent electrode units 60, and connectionelectrodes 64 for electrically connecting the electrode units 60,separated by the slits 62, to each other. In FIG. 32, the six electrodeunits 60 (twelve units in total) of three lines in the directionparallel to the gate bus line 12 and two lines in the direction parallelto the drain bus line 14 are disposed at each of both sides of thestorage capacitor bus line 18 in the vertical direction in the drawing.

In the liquid crystal display device shown in FIG. 32 and disclosed inpatent document 7, a portion where the electrode is not formed isprovided in the vicinity of a side or a corner of the electrode unit 60,and at the time of voltage application, the liquid crystal molecules inthe vertical alignment to the substrate are inclined in other directionsand are aligned by the oblique electric field generated in this portion.

In the liquid crystal display device disclosed in patent document 7, thepattern of the electrode unit 60 is solid all over the surface, and onlythe electric field at the outer peripheral part of the electrode unit 60causes the liquid crystal molecules to be inclined and aligned towardthe center part of the electrode unit 60. Thus, the size of theelectrode unit 60 which can incline and align the liquid crystalmolecules toward the center part by the oblique electric field of theouter peripheral part of the electrode unit 60 is limited. Specifically,in the case where the size of the electrode unit 60 is 50 μm or more,the control of a singular point of an alignment vector of the liquidcrystal molecule becomes difficult. Especially, at the outside of theelectrode unit 60, since there is no means for fixing the singularpoint, a fluctuation occurs in the occurrence position of the singularpoint. Thus, it becomes difficult to uniformly align the liquid crystalmolecules toward the center part of the electrode unit 60 from outside,and roughness occurs on the display. Besides, when an external force isapplied, for example, when the liquid crystal panel is pressed by afinger, it becomes difficult to return the once broken singular point tothe original state.

On the other hand, when an attempt is made to realize a liquid crystaldisplay device having two functions of a reflection type and atransmission type, liquid crystal display devices disclosed innon-patent document 1 and non-patent document 2 have difficulties asdescribed below.

First, with respective to the reflection type liquid crystal displaydevice disclosed in non-patent document 1, a use in combination with thetransmission type has not been realized. This is because the liquidcrystal layer is hybrid aligned on the assumption that light istransmitted through the liquid crystal layer twice. When the liquidcrystal layer of the hybrid alignment is used for the transmission type,its birefringence is small, and a sufficient white display can not berealized. Besides, there is a difficulty that viewing anglecharacteristics are inferior in the transmission type.

Besides, the transreflective type liquid crystal display devicedisclosed in non-patent document 2 includes the reflecting electrodehaving uneven reflecting surface. In order to form the reflectingelectrode having the uneven reflecting surface, in addition to themanufacture process of a normal transmission type liquid crystal displaydevice, a process, such as formation of a resin layer, patterning of theresin layer and formation of the reflecting electrode, is furtherrequired. Thus, there is a disadvantage that the manufacture cost israised.

Besides, in general, in the case where one liquid crystal display deviceis used for both the transmission type and the reflection type, theoptical paths in the transmission area and the reflection area becomedifferent from each other. In the transmission area, light from abacklight unit provided at a lower part of a liquid crystal panel istransmitted from the lower part of the liquid crystal panel to the upperpart, so that the display is realized. That is, in the transmissionarea, the light is transmitted through the liquid crystal layer onlyonce. On the other hand, in the reflection area, the light incident fromthe upper part of the liquid crystal panel is reflected at the lowerpart of the liquid crystal panel, and is again transmitted to the upperpart of the liquid crystal panel, so that the display is realized. Thatis, in the reflection area, the light is transmitted through the liquidcrystal layer twice. Thus, in the reflection area, as compared with thetransmission area, the optical effect by the liquid crystal layerbecomes twice, and there is a problem that the reflection area takes ona ting of yellow.

An object of this embodiment is to provide a liquid crystal displaydevice which can suppress the occurrence of uneven display and canobtain excellent display quality, and a method of manufacturing thesame.

Besides, another object of this embodiment is to provide a liquidcrystal display device which has functions of both the transmission typeand the reflection type, can be manufactured at low cost withoutincreasing a manufacture process of the transmission type, and canobtain excellent display quality, and a method of manufacturing thesame.

The above object is achieved by a liquid crystal display deviceincluding a first substrate which includes a plurality of gate bus linesdisposed almost in parallel with each other, a plurality of drain buslines disposed almost in parallel with each other to intersect with thegate bus lines, a plurality of thin film transistors respectivelyprovided at intersection parts between the gate bus lines and the drainbus lines, and a plurality of pixel electrodes respectively formed inpixel areas surrounded by the gate bus lines and the drain bus lines andrespectively connected to the plurality of thin film transistors, asecond substrate disposed to be opposite to the first substrate andhaving an opposite electrode opposite to the plurality of pixelelectrodes, and a liquid crystal layer sealed between the firstsubstrate and the second substrate and having a negative dielectricanisotropy, and characterized in that each of the pixel electrodesincludes a plurality of electrode units disposed through slits andelectrically connected to each other, and each of the electrode unitsincludes a solid part, and a plurality of extension parts extending fromthe solid part toward an outer peripheral direction of the electrodeunit.

Besides, the above object is achieved by a liquid crystal display deviceincluding a first substrate which includes a plurality of gate bus linesdisposed almost in parallel with each other, a plurality of drain buslines disposed almost in parallel with each other to intersect with thegate bus lines, a plurality of thin film transistors respectivelyprovided at intersection parts between the gate bus lines and the drainbus lines and a plurality of pixel electrodes respectively formed inpixel areas surrounded by the gate bus lines and the drain bus lines andrespectively connected to the plurality of thin film transistors, asecond substrate disposed to be opposite to the first substrate andhaving an opposite electrode opposite to the plurality of pixelelectrodes, and a liquid crystal layer sealed between the firstsubstrate and the second substrate and having a negative dielectricanisotropy, and characterized in that each of the pixel electrodesincludes a plurality of electrode units disposed through slits, havingsolid parts and electrically connected to each other, and the firstsubstrate further includes reflecting electrodes formed under areas inwhich the solid parts of all of or a part of the plurality of electrodeunits are formed.

Besides, the above object is achieved by a liquid crystal display deviceincluding a first substrate which includes a plurality of gate bus linesdisposed almost in parallel with each other, a plurality of drain buslines disposed almost in parallel with each other to intersect with thegate bus lines, a plurality of thin film transistors respectivelyprovided at intersection parts between the gate bus lines and the drainbus lines, a plurality of pixel electrodes respectively formed in pixelareas surrounded by the gate bus lines and the drain bus lines andrespectively connected to the plurality of thin film transistors, andreflecting electrodes partially formed under areas where the pluralityof pixel electrodes are formed, a second substrate disposed to beopposite to the first substrate and having an opposite electrodeopposite to the plurality of pixel electrodes, and a liquid crystallayer sealed between the first substrate and the second substrate andhaving negative dielectric anisotropy, and characterized in that athickness of the liquid crystal in reflection areas where the reflectingelectrodes are formed is thinner than that in other areas.

Besides, the above object is achieved by a liquid crystal display deviceincluding a first substrate which includes a plurality of gate bus linesdisposed almost in parallel with each other, a plurality of drain buslines disposed almost in parallel with each other to intersect with thegate bus lines, a plurality of thin film transistors respectivelyprovided at intersection parts between the gate bus lines and the drainbus lines, and a plurality of pixel electrodes respectively formed inpixel areas surrounded by the gate bus lines and the drain bus lines andrespectively connected to the plurality of thin film transistors, asecond substrate disposed to be opposite to the first substrate andhaving an opposite electrode opposite to the plurality of pixelelectrodes, and a liquid crystal layer sealed between the firstsubstrate and the second substrate and having a negative dielectricanisotropy, and characterized in that each of the pixel electrodesincludes a plurality of electrode units disposed through slits, havingsolid parts and electrically connected to each other, and the firstsubstrate further includes a reflecting electrode formed under an areain which the electrode unit is not formed in each of the pixel areas.

The liquid crystal display device according to this embodiment and amethod of manufacturing the same will be described with reference toFIGS. 33 to 40C.

First, the liquid crystal display device according to this embodimentwill be described with reference to FIGS. 33 to 37. FIG. 33 is a planview showing a structure of one pixel of the liquid crystal displaydevice according to this embodiment, FIG. 34 is a sectional view takenalong line A–A′ of FIG. 33, FIG. 35 is a view showing an arrangement ofa polarizing plate and the like of the liquid crystal display deviceaccording to this embodiment, FIG. 36 is a plan view showing a structureof one pixel in a case where an electrode unit is made of only a combelectrode, and FIG. 37 is a graph of measurement of a rate of change inbrightness with respect to a variation in width of an extension part ofthe comb electrode.

FIG. 33 shows the structure of one pixel of the liquid crystal displaydevice according to this embodiment. As shown in the drawing, aplurality of gate bus lines 12 extending in the horizontal direction inthe drawing are formed on a TFT substrate 2 in parallel with each otherat intervals of, for example, 300 μm (FIG. 33 shows two gate bus lines).A plurality of drain bus lines 14 almost vertically intersecting withthe gate bus lines 12 through an insulating film such as, for example, asilicon oxide film and extending in the vertical direction in thedrawing are formed in parallel with each other at intervals of, forexample, 100 μm (FIG. 33 shows two drain bus lines). The widths of boththe gate bus line 12 and the drain bus line 14 are, for example, 7 μm.Areas surrounded by the plurality of gate bus lines 12 and the drain buslines 14 are pixel areas. A storage capacitor bus line 18 crossingalmost the center of each of the pixel areas and extending almost inparallel with the gate bus line 12 is formed. A storage capacitorelectrode 19 is formed in each pixel on the storage capacitor bus line18 through an insulating film.

A TFT 20 is formed in the vicinity of each of intersection positionsbetween the gate bus lines 12 and the drain bus lines 14. A drainelectrode 36 of the TFT 20 is extended from the drain bus line 14, andis formed to be positioned at the side of one end side of an activelayer formed on the gate bus line 12 and a channel protective filmformed thereon. On the other hand, a source electrode 38 of the TFT 20is opposite to the drain electrode 36 through a predetermined gap, andis formed to be positioned at the side of the other end side of theactive layer and the channel protective film. The drain electrode 36,the active layer and the source electrode 38 are formed of, for example,the same semiconductor layer, and areas where impurities are injected athigh concentration are the drain electrode 36 and the source electrode38. An area just under the channel protective film of the gate bus line12 functions as a gate electrode of the TFT 20.

A pixel electrode made of a transparent conductive film of, for example,ITO (Indium Tin Oxide) is formed in the pixel area.

The pixel electrode 16 includes a plurality of electrode units 60 eachhaving a square outer periphery and smaller than the pixel area,electrode blank parts (slits) 62 formed between the adjacent electrodeunits 60, and connection electrodes 64 for electrically connecting theelectrode units 60, separated by the slits 62, to each other. In FIG.33, the six electrode units 60 (twelve units in total) of three lines inthe direction parallel to the gate bus line 12 and two lines in thedirection parallel to the drain bus line 14 are disposed at each of bothsides of the storage capacitor bus line 18 in the vertical direction inthe drawing. The plurality of electrode units 60 constituting the pixelelectrode 16 are formed of the same conductive film.

Each of the electrode units 60 includes an almost square solid part 46having sides almost parallel to or vertical to the gate bus line 12 andthe drain bus line 14. The length of one side of the square solid part46 is, for example 25 82 m.

Besides, the electrode unit 60 includes a stem part 48 branching fromthe center of each of the sides of the solid part 46 and extendingalmost in parallel with or vertically to the gate bus line 12 and thedrain bus line 14. The size of the stem part 48 is, for example, 5 μm inlength and 5 μm in width.

Further, the electrode unit 60 includes a plurality of branch parts 49branching from the solid part 46 and the stem part 48 and extendingobliquely with respect to the stem part 48 to form a comb shape, andelectrode blank parts (spaces) 66 between the adjacent branch parts 49.In an area partitioned by the adjacent stem parts 48, the respectivebranch parts 49 branching from the solid part 46 and the stem part 48extend almost in the same direction. In FIG. 33, the two small branchparts 49 branch from the one stem part 48, and the two large branchparts 49 are branch from one side of the solid part 46. That is, in thearea partitioned by the adjacent stem parts 48, the four branch parts 49extend in the same direction. Incidentally, in this specification, acomb portion of the electrode unit 60 in which the stem parts 48 as theextension parts and the branch parts 49 as the extension parts areformed through the blank parts 66 is called a comb electrode 53.

An angle between the stem part 48 and the branch part 49, in otherwords, an angle between the side of the outer periphery of the electrodeunit 60 and the branch part 49 is, for example, 450. The width of thebranch part 49 is, for example, 3 μm, and the width of the blank part 66is, for example, 3 μm.

The end of each of the branch parts 49 is formed to be almost parallelto or vertically to the gate bus line 12 and the drain bus line 14, andby this, the outer periphery of the electrode unit 60 is almost square.The length of one side of the square electrode unit 60 is, for example,35 μm.

As stated above, the square solid part 46 with one side having a lengthof, for example, 25 μm is formed at the center part of the electrodeunit 60 having the square outer periphery with one side of, for example,35 μm, and the comb electrode 53 is formed in an area having a width of5 μm from the outer periphery of the electrode unit 60 toward theinside. Incidentally, although the width of the area where the combelectrode 53 is formed is not limited to this, it is preferable that thearea where the comb electrode 53 is formed has a width of 5 μm or morefrom the outer periphery of the electrode unit 60 toward the inside.This is because when the width is smaller than this, it becomesdifficult to accurately pattern the comb electrode 53.

The adjacent electrode units 60 are electrically connected to each otherby the connection electrode 64 formed to be connected to the stem parts48 positioned at the centers of the respective facing sides. As statedabove, by providing the connection electrode 64 to connect the centersof the respective facing sides of the adjacent electrode units 60, thesingular point can be certainly fixed.

Besides, at the lower part of the pixel area in the drawing, the drainelectrode 36 of the TFT 20 of the pixel area adjacent to the lower partis formed to protrude. When the pixel electrode 16 is formed to overlapwith the drain electrode 36 when viewed in the direction vertical to thesubstrate surface, a disturbance occurs in the alignment of liquidcrystal molecules in this area, and there is a possibility that crosstalk occurs. Thus, it is necessary that the pixel electrode 16 and thedrain electrode 36 are formed not to overlap with each other. Thus, theshape of the outer periphery of the electrode unit 60 (lower left inFIG. 33) corresponding to this area is formed into such a shape that apart of the square is cut away in accordance with the shape of the drainelectrode 36. Specifically, while the shape of the outer periphery ofthe other electrode unit 60 has, for example, a square shape of 35 μm×35μm, the shape of the electrode unit 60 in this area has such a shapethat a part of the square is cut away so that it is spaced from thedrain electrode 36 by, for example, 7 μm.

The pixel electrode 16 is electrically connected to the source electrode38 through a contact hole formed in an insulating film under the solidpart 46 of the electrode unit 60 (upper left in FIG. 33) close to theTFT 20. The shape of the contact hole is, for example, a square havingone side of 5 μm. Here, it is preferable that the upperpart of theconductive film of the source electrode 38 in the area where theelectrode unit 60 close to the TFT 20 is formed, is covered with theconductive film of the pixel electrode 16. This is because when theconductive film of the source electrode 38 is positioned in the area ofthe slit 62 of the electrode unit 60, the oblique electric field by theslit 62 is not sufficiently generated, and there is a fear that thealignment control of liquid crystal in this area becomes insufficient.

Besides, a rectangular contact area 67 is formed in the pixel electrode16 on the storage capacitor electrode 19 through an insulating film. Thecontact area 67 is electrically connected to the stem part 48 of theadjacent electrode unit 60 through the connection electrode 64. Thepixel electrode 16 is electrically connected to the storage capacitorelectrode 19 through the contact hole formed in the insulating filmunder the contact area 67.

A BM (Black Matrix) as a light shielding layer for shading the end partof the pixel area is formed at the side of a CF substrate 4 disposed tobe opposite to the TFT substrate 2. The BM is formed into a latticehaving a width of, for example, 23 μm. A lattice interval in theextending direction of the gate bus line 12 is 100 μm, and a latticeinterval in the extending direction of the drain bus line 14 is 300 μm.A CF resin layer of one of red (G), green (G) and blue (B) is formed inthe opening part of the BM. The opposite electrode (common electrode)made of, for example, ITO is formed on the whole surface of the CF resinlayer.

FIG. 34 is a sectional view taken along line A–A′ of FIG. 33. As shownin the drawing, the drain bus lines 14 are formed on a glass substrate10 constituting the TFT substrate 2. An insulating film 30 is formed onthe glass substrate 10 on which the drain bus lines 14 are formed. Thepixel electrode 16 is formed on the insulating film 30 between the drainbus lines 14.

On the other hand, the CF substrate 4 disposed to be opposite to the TFTsubstrate 2 includes a glass substrate 11 and an opposite electrode 42formed on the surface of the glass substrate 11 opposite to the TFTsubstrate 2. Incidentally, the CF resin layer (not shown) is formedbetween the glass substrate 11 and the opposite electrode 42.

Further, as shown in FIGS. 33 and 34, a cylindrical protruding structure73 is provided on the surface opposite to the TFT substrate 2 so that itis positioned almost at the center of each of the electrode units 60 ofthe TFT substrate 2. The protruding structure 73 is made of, forexample, acryl resin, and its size is 10 μm in diameter and 2 μm inheight.

Besides, alignment films (not shown) are formed on the facing surfacesof both the substrates 2 and 4. The alignment film has a verticalalignment, and causes liquid crystal molecules to be aligned in thedirection vertical to the substrate surface (alignment film surface) ina steady state. The liquid crystal display device is manufactured byinjecting and sealing the liquid crystal having a negative dielectricanisotropy into the liquid crystal cell in which both the substrates 2and 4 are bonded to each other.

FIG. 35 shows an arrangement of a polarizing plate and the like of theliquid crystal display device according to this embodiment. As shown inthe drawing, polarizing plates 86 and 87 disposed crossed Nicols aredisposed at both sides of a liquid crystal layer 6 made of the liquidcrystal cell in which the liquid crystal is sealed. A quarter-wave plate50 is disposed between the liquid crystal layer 6 and the polarizingplate 87. Besides, a quarter-wave plate 51 is disposed between theliquid crystal layer 6 and the polarizing plate 86. As the quarter-waveplates 50 and 51, for example, ARTON plates (in-plane phase differenceis 140 nm) made by JSR Corporation can be used. A layer having anegative phase difference, such as a TAC (triacetylcellulose) film 72,may be disposed between the liquid crystal layer 6 and the quarter-waveplate 51 in order to improve the viewing angle characteristics.Incidentally, an upper part in the drawing is an observer side and alower part in the drawing is an optical source side where a backlightunit is disposed. A reflection polarizing plate 75 is disposed betweenthe polarizing plate 87 and the light source side. As the reflectionpolarizing plate 75, for example, PCF 350D made by Nitto Denko Co., Ltd.can be used.

An angle between the optical axis (lag axis) of the quarter-wave plate50 and the absorption axis of the polarizing plate 87 is approximately45°. That is, when light emitted from a light source is transmittedthrough the polarizing plate 87 and the quarter-wave plate 50 in thisorder, it becomes a circularly polarized light. Besides, an anglebetween the optical axis of the quarter-wave plate 51 and the absorptionaxis of the polarizing plate 86 is approximately 45°. The optical axesof both the quarter-wave plates 50 and 51 are almost orthogonal to eachother. In order to realize the symmetry of viewing angles and optimizethe viewing angle characteristics in the vertical and horizontaldirections with respect to the display screen, the polarizing plates 86and 87, and the quarter-wave plates 50 and 51 are disposed as describedbelow.

The absorption axis of the polarizing plate 87 is disposed in thecounterclockwise direction of 150° with reference to the right part(direction of three o'clock) of the display screen. The optical axis ofthe quarter-wave plate 50 is disposed in the counterclockwise directionof 15° with reference to the right part of the display screen. Theoptical axis of the TAC film 72 and the optical axis of the quarter-waveplate 51 disposed at the observer side of the liquid crystal layer 6 aredisposed in the counterclockwise direction of 105° with reference to theright part of the display screen. The absorption axis of the polarizingplate 86 is disposed in the counterclockwise direction of 60° withreference to the right part of the display screen.

In this way, the liquid crystal display device according to thisembodiment is constructed.

In the liquid crystal display device according to this embodimentconstructed as described above, when a voltage is applied between theopposite electrode 42 and the pixel electrode 16, the liquid crystal isput in an alignment state described below.

In the area of the electrode unit 60 where the comb electrode 53 isformed, the liquid crystal molecule is aligned in the extensiondirection of the blank part 66 between the branch parts 49 by the combelectrode 53. On the other hand, in the area of the center part of theelectrode unit 60 where the solid part 46 is formed, the liquid crystalmolecule is aligned in the direction toward the center part of theelectrode unit 60 by the oblique electric field of the outer peripheralpart of the solid part 46 and by the liquid crystal alignment from theoutside due to the comb electrode 53. That is, the alignment division infour directions is roughly realized.

One of the main features of the liquid crystal display device accordingto this embodiment is that each of the plurality of electrode units 60constituting the pixel electrode 16 of one pixel includes the squaresolid part 46, the stem part 48 branching from the center of each of thesides of the solid part 46 and extending almost in parallel with orvertically to the gate bus line 12 and the drain bus line 14, and theplurality of branch parts 49 branching from the solid part 46 and thestem part 48 and extending obliquely with respect to the stem part 48 toform the comb shape.

In the vertical alignment type liquid crystal display device, it isconceivable that as a method of performing alignment control of theliquid crystal, as shown in FIG. 36, slits are provided on almost thewhole surface of an electrode unit 60, a solid part 46 is not provide,and the electrode unit 60 is formed of only a comb electrode 53 of stemparts 48 and branch parts 49. In this case, as shown in FIG. 36, theelectrode unit 60 includes the two stem parts 48 extending almost inparallel with or vertically to the gate bus line 12 and the drain busline 14 and intersecting with each other crosswise. Further, theelectrode unit 60 includes the plurality of branch parts 49 branchingfrom the stem parts 48 and extending obliquely with respect to the stemparts 48 to form the comb shape, and electrode blank parts 66 betweenthe adjacent branch parts 49. In the area partitioned by the adjacentstem parts 48, the respective branch parts 49 branching from the stemparts 48 extend in almost the same direction.

However, as shown in FIG. 36, when the electrode unit 60 is patterned,it is difficult to make the widths of the slits constant in all areas interms of process. Besides, at the time of patterning, all display areais divided into a plurality of areas, and when the patterning of thepixel electrode is performed for each of the divided areas, a variationin slit width becomes large at the boundary portion between the dividedareas. In the case where the variation in the slit width occurs, thatis, in the case where the variation occurs in the width of the stem part48 and the branch part 49, a difference in brightness occurs when adisplay is actually performed, and as a result, uneven display occurs.

On the other hand, in the liquid crystal display device according tothis embodiment, the square solid part 46 is provided at the center ofthe electrode unit 60, and the stem parts 48 and the branch parts 49branch from the solid part 46. Thus, as compared with the case shown inFIG. 36, the ratio of the stem parts 48 and the branch parts 49 to theelectrode unit 60, that is, the ratio of the comb electrode 53 is small.Accordingly, it becomes possible to suppress the occurrence of thedifference in brightness due to the variation in the widths of the stemparts 48 and the branch parts 49, to reduce the uneven display, and toobtain excellent display quality.

Incidentally, in order to sufficiently suppress the occurrence of thedifference in brightness due to the variation in the widths of the stemparts 48 and the branch parts 49, it is preferable that the ratio of thesquare measure of the solid part 46 to the square measure of the areawithin the outer periphery of the electrode unit 60 is 50% or more.

FIG. 37 is a graph of measurement of a rate of change in brightness withrespect to a variation in width of the stem part 48 and the branch part49 (extension part) of the comb electrode 53. In FIG. 37, a graph 1 is agraph in the case where the ratio of the square measure of the solidpart 46 to the square measure of the area within the outer periphery ofthe electrode unit 60 is 58%. A graph 2 is a graph in the case where theratio of the square measure of the solid part 46 to the square measureof the area within the outer periphery of the electrode unit 60 is 50%.A graph 3 is a graph in the case where the ratio of the square measureof the solid part 46 to the square measure of the area within the outerperiphery of the electrode unit 60 is 33%. A graph 4 is a graph in thecase shown in FIG. 36 in which the electrode unit 60 is formed of onlythe comb electrode 53 and the solid part 46 is not provided.

From the graphs shown in FIG. 37, it is understood that as compared withthe case shown in FIG. 36 in which the electrode unit 60 is formed ofonly the comb electrode 53, the change in the brightness can besuppressed by providing the solid part 46. Further, as described above,it is understood that when the ratio of the square measure of the solidpart 46 to the square measure of the area within the outer periphery ofthe electrode unit 60 is made 50% or more, the change in the brightnesscan be sufficiently suppressed.

Besides, in the liquid crystal display device according to thisembodiment, since the solid part 46 is provided at the center part ofthe electrode unit 60, as compared with the case shown in FIG. 36 inwhich the electrode unit 60 is formed of only the comb electrode 53, thelengths of the stem part 48 and the branch part 49 of the comb electrode53 are short. Thus, as compared with the case shown in FIG. 36, theliquid crystal display device according to this embodiment can improvethe response speed of the liquid crystal molecule. The reason is asfollows. That is, in the case where the length of the comb electrode 53is long as shown in FIG. 36, a liquid crystal portion which is hardlyinfluenced by a surrounding oblique electric field is generated at amidway position of the comb electrode 53. At this position, it becomesdifficult to determine whether a direction in which the liquid crystalis aligned is a direction toward the center with respect to the combelectrode 53, or a direction toward the outer peripheral part. On theother hand, as in the liquid crystal display device according to thisembodiment, when the length of the comb electrode 53 is short becausethe solid part 46 is formed, the liquid crystal is apt to be influencedby the surrounding oblique electric field, and the alignment angle atwhich the liquid crystal molecule is aligned becomes easy to determine.As a result, the response speed of the liquid crystal molecule becomesfast.

Besides, in the liquid crystal display device according to thisembodiment, the quarter-wave plates 50 and 51 and the polarizing plates87 and 86 are disposed at the outside of both the substrates 2 and 4 inthis order. By doing so, as compared with the case where only thepolarizing plates 87 and 86 disposed in crossed Nicols are used, thequarter-wave plates 50 and 51 whose optical axes are orthogonal to eachother are disposed, so that the transmissivity of light at the time ofwhite display can be improved, and it is possible to realize the liquidcrystal display device in which the brightness is high and the cleardisplay can be obtained. In the case where the quarter-wave plates 50and 51 are not disposed, a dark line is generated at a position of aboundary where the domain direction is not divided into four. Besides,in an area where the comb electrode 53 does not exist, differently fromthe area where the comb electrode 53 exists, it is difficult to give adirection angle in a specific direction. Thus, as compared with the casewhere the comb electrode 53 exists in the whole area, the brightness islowered. Since all the dark lines generated in these portions can bemade transparent by disposing the quarter-wave plates 50 and 51, thetransmissivity can be improved.

Next, a method of manufacturing the liquid crystal display deviceaccording to this embodiment will be described with reference to FIGS.38A to 40C. FIGS. 38A to 40C are process sectional views showing themethod of manufacturing the liquid crystal display device according tothis embodiment, and correspond to the section in the direction alongthe drain bus line 14 of FIG. 33. Incidentally, in the following, adescription will be given to the method up to the formation of the pixelelectrode 16 on the glass substrate 10 of the TFT substrate 2.

First, a gate layer 21 made of an aluminum film is formed on the glasssubstrate 10 by, for example, a sputtering method (see FIG. 38A).

Next, the gate layer 21 is patterned, so that a gate bus line 12 and astorage capacitor bus line 18 are formed (see FIG. 38B). Incidentally,in FIGS. 38A to 40C, the storage capacitor bus line 18 is omitted.

Next, an insulating film 22 made of a silicon oxide film is formed onthe whole surface by, for example, a CVD (Chemical Vapor Deposition)method (see FIG. 38C).

Next, a semiconductor layer 23 made of a polysilicon film is formed onthe insulating film 22 by, for example, the CVD method (see FIG. 38D).

Next, an impurity is ion implanted into the semiconductor layer 23 otherthan an area on the gate bus line 12, which becomes an active layer 24(see FIG. 39A).

Next, the semiconductor layer 23 in which the impurity is ion implantedis patterned, so that a drain bus line 14, a drain electrode 36, asource electrode 38 and a storage capacitor electrode 19 are formed (seeFIG. 39B). In this way, a TFT 20 is formed in the vicinity of anintersection position of the gate bus line 12 and the drain bus line 14.

Next, an insulating film 25 made of a silicon oxide film is formed onthe whole surface by, for example, the CVD method (see FIG. 39C).

Next, the insulating film 25 is selectively etched, so that a contacthole 26 reaching the source electrode 38 of the TFT 20 is formed (seeFIG. 40A).

Next, a transparent conductive film 27 made of ITO is formed on thewhole surface by, for example, the sputtering method (see FIG. 40B).

Next, the transparent conductive film 27 is patterned, so that anelectrode unit 60, a connection electrode 64 and a contact area 67 areformed (see FIG. 40C). In this way, the pixel electrode 16 electricallyconnected to the source electrode 38 through the contact hole 26 isformed on the glass substrate 10 of the TFT substrate 2.

Although not shown, subsequently to this, a process similar to amanufacture process of a normal liquid crystal display device isperformed, so that the liquid crystal display device according to thisembodiment can be completed.

As stated above, according to this embodiment, the square solid part 46is provided at the center of the electrode unit 60, and the ratio of thecomb electrode 53 to the electrode unit 60 is small, so that theoccurrence of difference in brightness due to the variation in width ofthe comb electrode 53 is suppressed, and the uneven display can bereduced. By this, the liquid crystal display device excellent in displayquality can be provided.

MODIFIED EXAMPLE

A liquid crystal display device according to a modified example of thisembodiment will be described with reference to FIGS. 41A to 41N. FIGS.41A to 41N are plan views showing shapes of electrode units in theliquid crystal display device according to this modified example.

In the above, as shown in FIG. 33, although the square solid part 46 isprovided at the center part of the electrode unit 60, the shape of theelectrode unit 60 can be made to have various shapes other than this.

For example, as shown in FIG. 41A, the shape of the solid part 46 may bemade a rhombic shape obtained by connecting center points of therespective sides of the outer periphery of the electrode unit 60.Incidentally, the rhombic solid part 46 may be smaller than that shownin FIG. 41A, and its shape may be distorted.

Besides, as shown in FIG. 41B, the shape of the solid part 46 may bemade a circular shape. Besides, the shape of the solid part 46 may bemade an elliptic shape.

Besides, as shown in FIG. 41C, the shape of the solid part 46 may bemade a convex polygon. Here, the convex polygon is the polygon in whichall angles are less than 180°.

Besides, as shown in FIG. 41D, the shape of the solid part 46 may bemade a cruciform shape wider than the stem part 48.

Besides, as shown in FIG. 41E, the shape of the solid part 46 may bemade a concave polygon. Here, the concave polygon is the polygon inwhich at least one angle is larger than 180°.

Besides, in the above, although the solid part 46 is provided almost thecenter part of the electrode unit 60, the position where the solid part46 is provided is not limited to the center part.

For example, as shown in FIGS. 41F and 41G, the solid part 46 iscontinuously formed between two opposite sides of the outer periphery ofthe electrode unit 60, and the comb electrode 53 may be formed at theother two sides, that is, at both sides of the solid part 46continuously formed between the two opposite sides. The direction inwhich the solid part 46 is continuously formed may be almost parallel tothe drain bus line 14 or may be parallel to the gate bus line 12.

Besides, as shown in FIG. 41H, the comb electrode 53 is formed in anarea close to one side of the outer periphery of the electrode unit 60,and the other area may be made the solid part 46. Incidentally, theliquid crystal display device including the electrode unit 60 having theshape shown in FIG. 41H will be described in a fourth embodiment.

Besides, as shown in FIG. 41I, similarly to FIG. 41D, the shape of thesolid part 46 may be made a cruciform shape, and the solid part 46 maybe continuously formed between two opposite sides of the outer peripheryof the electrode unit 60 in one direction of the cross.

Besides, as shown in FIG. 41J, the comb electrode 53 is formed in a halfarea of the electrode unit 60, and the other half area may be made thesolid part 46.

Besides, as shown in FIG. 41K, among four areas divided by the stemparts 48 extending crosswise from the center of the electrode unit 60toward the center points of the outer periphery of the electrode unit60, one pair of areas positioned diagonally are made the solid part 46,and the comb electrode 53 may be formed in each of the other pair ofareas positioned diagonally. As stated above, the four areas are definedin the electrode unit 60 by the cross-shaped boundary lines, the combelectrode 53 is formed in at least one of the four areas, and the solidpart 46 may be formed in the other areas.

Besides, in the above, although the description has been given to thecase where the electrode unit 60 is divided into the four square areasby the stem parts 48 crosswise extending from the center of theelectrode unit 60 toward the center points of the outer periphery of theelectrode unit 60, the division shape of the electrode unit 60 may beanother shape.

For example, as shown in FIG. 41L, the electrode unit is divided intofour triangular areas by the stem parts 48 crosswise extending from thecenter of the electrode unit 60 toward vertexes of the outer peripheryof the electrode unit 60, and the square solid part 46 may be providedat the center part of the electrode unit 60. In this case, the branchparts 49 branch from the solid part 46 and the stem parts 48, and extendobliquely with respect to the stem parts 48 to form the comb shape. Inthe triangular area divided by the adjacent stem parts 48, the branchparts 49 branching from the solid part 46 and the stem parts 48 extendin almost the same direction. An angle between the stem part 48 and thebranch part 49 is, for example, approximately 45°, in other words, anangle between the side of the outer periphery of the electrode unit 60and the branch part 49 is, for example, approximately 90°.

Besides, as shown in FIG. 41M, the electrode unit is divided into fourtriangular areas by the stem parts 48 provided on the diagonal lines ofthe electrode unit 60 having the square outer periphery, and the solidpart 46 may be provided in one area of them. In this case, in the othertriangular areas, the branch parts 49 branch from the stem parts 48, andextend obliquely with respect to the stem parts 48 to form the combshape. In the triangular are a partitioned by the adjacent stem parts48, the branch parts 49 branching from the solid part 46 and the stemparts 48 extend in almost the same direction. An angle between the stempart 48 and the branch part 49 is, for example, approximately 45°.

Besides, as shown in FIG. 41N, the electrode unit is divided into fourtriangular areas by the stem parts 48 provided on diagonal lines of theelectrode unit 60 having the square outer periphery, and the solid part46 may be provided in one pair of areas symmetric with respect to thecenter point of the electrode unit 60. In this case, in the other pairof areas symmetric with respect to the point, the branch parts 49branches from the stem parts 48, and extend obliquely with respect tothe stem parts 48 to form the comb shape. In the triangular areapartitioned by the adjacent stem parts 48, the branch parts 49 branchingfrom the solid part 46 and the stem parts 48 extend in almost the samedirection. An angle between the stem part 48 and the branch part 49 is,for example, approximately 45°.

As shown in FIGS. 41M and 41N, the four areas are defined in theelectrode unit 60 by the diagonal lines of the outer periphery of theelectrode unit 60, the comb electrode 53 is formed in at least one ofthe four areas, and the solid part 46 may be formed in the other area.Incidentally, as shown in FIG. 41N, among the four areas, the combelectrodes 53 are formed in one pair of areas positioned diagonally andthe solid parts 46 are formed in the other pair of areas, and the onepair of areas in which the comb electrodes 53 are formed may becomeareas including the sides almost parallel to the drain bus line 14 ofthe outer periphery of the electrode unit 60.

Besides, as shown in FIGS. 41A to 41N, the shape of the electrode unit60 is not limited to those in which the branch parts 49 extend almost inparallel with each other in the area partitioned by the adjacent stemparts 48. For example, in the electrode unit 60, a plurality ofextension parts (stem parts 48, branch parts 49) branching from thesolid part 46 may be formed so as to extend in the radial direction fromthe center part of the electrode unit 60 toward the outer periphery ofthe electrode unit 60.

FOURTH EMBODIMENT

A liquid crystal display device according to a fourth embodiment of thisinvention will be described with reference to FIG. 42. FIG. 42 is a planview showing a structure of one pixel of the liquid crystal displaydevice according to this embodiment. Incidentally, structural elementssimilar to those of the liquid crystal display device of the thirdembodiment are denoted by the same reference numerals, and theirdescription will be omitted or simplified.

The basic structure of the liquid crystal display device according tothis embodiment is almost the same as the liquid crystal display deviceaccording to the third embodiment except for the shape of an electrodeunit 60 constituting a pixel electrode 16. A main feature of the liquidcrystal display device according to this embodiment is that in theelectrode unit 60, a comb electrode 53 is formed in an area close to oneside of a square outer periphery at a drain bus line 14 side, and theother area is a solid part 46.

In the liquid crystal display device according to this embodiment, asshown in FIG. 42, in the electrode unit 60 having the square outerperiphery, the comb electrode 53 made of a stem part 48 and branch parts49 is formed in the area close to one side, adjacent to the drain busline 14, of the sides of the outer periphery parallel to the drain busline 14. The other area of the electrode unit 60 is the solid part 46.The solid part 46 is formed to have a width of, for example 28 μm fromthe side, farther from the drain bus line 14, of the sides of the outerperiphery parallel to the drain bus line 14. In this case, the area of80% of the electrode unit 60 having the square outer periphery of 35μm×35 μm is the solid part 46.

An adjacent electrode unit 60 is electrically connected by a connectionelectrode 64 formed to be connected to the solid part 46.

In the electrode unit 60 of the liquid crystal display device accordingto this embodiment, the reason why the comb electrode 53 is formed inthe area close to the one side of the square outer periphery at thedrain bus line 14 side is as follows.

Similarly to the case of the third embodiment, the adjacent electrodeunit 60 is disposed to be separated by a slit 62, and the connectionelectrode 64 is formed to connect center parts of the sides of the outerperipheries of the adjacent electrode units 60.

In the electrode unit 60, at the side where the connection electrode 64is connected. That is, among the four sides of the outer periphery ofthe electrode unit 60, the control of singular points of the three sidesto which the connection electrodes 64 are connected is suitablyperformed.

The domain of liquid crystal in the vicinity of the drain bus line 14 ispulled by the flow of this singular point, and an inclination alignmentoccurs in an unexpected vertical direction. As a result, the balance ofalignment division of the liquid crystal is lost, roughness of thedisplay occurs, and a mark remains in the case where the liquid crystalpanel is pressed by a finger.

In the liquid crystal display device according to this embodiment, sincethe area of the comb electrode 53 is provided along the drain bus line14, the alignment of the liquid crystal at the end part of the drain busline 14 is clearly divided into two areas of an upper direction (in FIG.42, upper right direction/upper left direction) and a lower direction(in FIG. 42, lower right direction/lower left direction) by this combelectrode 53. Since the two alignment areas are provided, the domain ofthe liquid crystal divided into upper and lower parts passes through theportion of the stem part 48 without fail. By this, it is possible toobtain such effects that the disturbance of the domain of the liquidcrystal along the drain bus line 14 can be prevented, the roughness ofthe display is suppressed, and a mark does not remain in the case wherean outer force is applied, for example, the liquid crystal panel ispressed by a finger.

Besides, as compared with the liquid crystal display device according tothe third embodiment, in the liquid crystal display device according tothis embodiment, since the square measure of the solid part 46 in theelectrode unit 60 is large, the occurrence of brightness difference oruneven display due to the dimension variation of the comb electrode 53can be further effectively suppressed.

FIFTH EMBODIMENT

A liquid crystal display device according to a fifth embodiment of theinvention will be described with reference to FIG. 43. FIG. 43 is a planview showing a structure of one pixel of the liquid crystal displaydevice according to this embodiment. Incidentally, structural elementssimilar to those of the liquid crystal display device according to thethird embodiment are denoted by the same reference number, and theirdescription will be omitted or simplified.

The basic structure of the liquid crystal display device according tothis embodiment is almost the same as the liquid crystal display deviceaccording to the third embodiment except for the shape of an electrodeunit 60 constituting a pixel electrode 16. The liquid crystal displaydevice according to this embodiment is different from the liquid crystaldisplay device according to the third embodiment in that the electrodeunit 60 has a rectangular outer periphery.

As shown in FIG. 43, the pixel electrode 16 in the liquid crystaldisplay device according to this embodiment has the rectangular outerperiphery, and includes a plurality of electrode units 60 smaller thanthe pixel area, a slit 62 formed between the adjacent electrode units60, and a connection electrode 64 for electrically connecting theelectrode units 60, separated by the slit 62, to each other. In FIG. 43,the three electrode units 60 (six units in total) of three lines in thedirection parallel to a gate bus line 12 and one line in the directionparallel to a drain bus line 14 are disposed at each of both sides of astorage capacitor bus line 18 in the vertical direction in the drawing.

The electrode unit 60 includes an almost rectangular solid part 46having sides almost parallel to or vertical to the gate bus line 12 andthe drain bus line 14. The width of the rectangular solid part 46 in thedirection parallel to the gate bus line 12 is, for example, 60 μm.Besides, the width of the rectangular solid part 46 parallel to thedrain bus line 14 is, for example, 25 μm.

Besides, the electrode unit 60 includes a stem part 48 branching fromthe center of each of sides of the solid part 46 and extending almost inparallel with or vertically to the gate bus line 12 and the drain busline 14. The size of the stem part 48 extending almost in parallel withthe gate bus line 12 is, for example, 9 μm in length and 5 μm in width.The size of the stem part 48 extending almost in parallel with the drainbus line 14 is, for example, 5 μm in length and 5 μm in width.

Further, the electrode unit 60 includes a plurality of branch parts 49branching from the solid part 46 and the stem part 48 and extendingobliquely with respect to the stem part 48 to form a comb shape, andelectrode blank parts 66 between the adjacent branch parts 49. In anarea partitioned by the adjacent stem parts 48, the branch parts 49branching from the solid part 46 and the stem parts 48 extend in almostthe same direction. In FIG. 43, the six branch parts 49 extend in thesame direction in the area partitioned by the adjacent stem parts 48.

An angle between the stem part 48 and the branch part 49 is, forexample, 45°. The width of the branch part 49 is, for example, 3 μm, andthe width of the blank part 66 is, for example, 3 μm.

Similarly to the liquid crystal display device according to the thirdembodiment, the end part of each of the branch parts 49 is formed almostin parallel with or vertically to the gate bus line 12 and the drain busline 14, and by this, the outer periphery of the electrode unit 60becomes almost rectangular. The width of the outer periphery of theelectrode unit 60 in the direction parallel to the gate bus line 12 is,for example, 78 μm. Besides, the width in the direction parallel to thedrain bus line 14 is, for example, 35 μm.

The adjacent electrode units 60 are electrically connected to each otherby the connection electrode 64 formed to be connected to the stem parts48 positioned at the centers of the respective sides of the outerperipheries of the electrode units 60. Since the electrode units 60 inonly one line is provided in the direction parallel to the drain busline 14, the connection electrode 64 is formed only in the directionparallel to the drain bus line 14.

Besides, in the lower part of the pixel area in the drawing, a drainelectrode 36 of a TFT 20 of a lower adjacent pixel area is formed toprotrude. From the same reason as the case of the third embodiment, theshape of the electrode unit 60 (at the lower part in FIG. 43) positionedin this area is formed into such a shape that a part of the rectanglecorresponding to the shape of the drain electrode 36 is cut away.Specifically, while the shape of the outer periphery of the otherelectrode unit 60 is a rectangular shape of 35 μm×78 μm, the shape ofthe outer periphery of the electrode unit 60 in this area is such ashape that a part of the rectangle is cut away so that it is spaced fromthe drain electrode by 7 μm.

A main feature of the liquid crystal display device according to thisembodiment is that the electrode unit 60 includes the rectangular solidpart 46 having the same long axis direction as the rectangular outerperiphery.

In the case where the outer peripheral shape of the electrode unit 60 isrectangular, when the square solid part 46 is merely formed as in thecase according to the third embodiment, the areal ratio of the solidpart 46 to the electrode unit 60 becomes small. Thus, it is conceivablethat even if the solid part 46 is formed, the effect to suppress thechange of brightness due to the variation of width of the comb electrode53 can not be sufficiently obtained. On the other hand, in the casewhere almost all area of the electrode unit 60 is made the solid part46, since the outer peripheral shape of the electrode unit 60 isrectangular, it is conceivable that the control of a singular pointbecomes difficult.

In the liquid crystal display device according to this embodiment, inthe electrode unit 60 having the rectangular outer periphery, therectangular solid part 46 having the same long axis direction as theouter periphery is formed in conformity with the shape of the outerperiphery of the rectangular shape. Thus, the change of brightness dueto the variation of width of the comb electrode 53 can be sufficientlysuppressed, and the control of the singular point does not becomedifficult.

Incidentally, also in the liquid crystal display device according tothis embodiment, similarly to the case of the liquid crystal displaydevice according to the third embodiment in which the outer periphery ofthe electrode unit 60 is square, in order to sufficiently suppress theoccurrence of the difference in brightness due to the variation in widthof the branch part 49, it is preferable that the ratio of the squaremeasure of the solid part 46 to the square measure of the area withinthe outer periphery of the electrode unit 60 is a predetermined value ormore, for example, 50% or more.

MODIFIED EXAMPLE

A liquid crystal display device according to a modified example of thefifth embodiment of the invention will be described with reference toFIGS. 44A to 44C. FIGS. 44A to 44C are plan views showing shapes ofelectrode units in the liquid crystal display device according to thismodified example.

In the above, as shown in FIG. 43, although the rectangular solid part46 is provided at the center part of the electrode unit 60 having therectangular outer periphery, similarly to the case according to themodified example of the third embodiment shown in FIGS. 41A to 41N, theshape of the electrode unit 60 can be made various shapes in addition tothis.

For example, the shape of the solid part 46 may be made an ellipticalshape as shown in FIG. 44A.

Besides, as shown in FIG. 44B, the shape of the solid part 46 may bemade a rhombic shape formed by connecting the center points of therespective sides of the outer periphery of the electrode unit 60.Incidentally, the rhombic solid part 46 may be smaller than that shownin FIG. 44B, and the shape may be distorted.

Besides, for example, as shown in FIG. 44C, the shape of the solid part46 maybe made a band shape reaching two opposite sides of the outerperiphery of the electrode unit 60, and the comb electrodes 53 may beformed at the other two sides, that is, at both sides of the band-shapedsolid part 46. Incidentally, the liquid crystal display device includingthe electrode unit 60 having the shape shown in FIG. 44C will bedescribed in detail in a sixth embodiment.

SIXTH EMBODIMENT

A liquid crystal display device according to a sixth embodiment of theinvention will be described with reference to FIG. 45. FIG. 45 is a planview showing a structure of one pixel of the liquid crystal displaydevice according to this embodiment. Incidentally, structural elementssimilar to those of the liquid crystal display device according to thefifth embodiment are denoted by the same reference numerals, and theirdescription will be omitted or simplified.

The basic structure of the liquid crystal display device according tothis embodiment is almost the same as the liquid crystal display deviceaccording to the fifth embodiment except for the shape of an electrodeunit 60 constituting a pixel electrode 16. A main feature of the liquidcrystal display device according to this embodiment is that in theelectrode unit 60, comb electrodes 53 are formed in areas close to thetwo sides of the rectangular outer periphery at the drain bus line 14side, and the other area is a solid part 46.

As shown in FIG. 45, in the electrode unit 60 having the rectangularouter periphery, the comb electrodes 53 each made of a stem part 48 andbranch parts 49 are formed in the areas close to the two sides of theouter periphery parallel to the drain bus line 14. In the case where thewidth of the outer periphery of the electrode unit 60 is made, forexample, 35 μm×78 μm similarly to the liquid crystal display deviceaccording to the fifth embodiment, the widths of the areas where thecomb electrodes 53 are formed are respectively, for example, 7 μm fromthe two sides of the outer periphery of the electrode unit 60 parallelto the drain bus line 14. In this case, the width of the solid part 46in the direction parallel to the gate bus line 12 is 64 μm.

In the liquid crystal display device according to this embodiment,similarly to the liquid crystal display device according to the fourthembodiment, since the comb electrode 53 is formed in the area along thedrain bus line 14, by this comb electrode 53, the alignment of liquidcrystal at the end part of the drain bus line 14 is clearly divided intotwo areas of the upper direction (in FIG. 45, upper rightdirection/upper left direction) and the lower direction (in FIG. 45,lower right direction/lower left direction). Since the two alignmentareas are provided as stated above, the domain of the liquid crystaldivided vertically passes through the portion of the stem part 48without fail. By this, it is possible to obtain such effects that thedisturbance of the domain of the liquid crystal along the drain bus line14 can be prevented, roughness of the display is suppressed, and in thecase where outer force is applied, for example, the liquid crystal panelis pressed by a finger, a mark does not remain.

Besides, in the liquid crystal display device according to thisembodiment, as compared with the liquid crystal display device accordingto the fifth embodiment including the electrode unit 60 having therectangular outer periphery, since the square measure of the solid part46 is large in the electrode unit 60, it is possible to furthereffectively suppress the occurrence of brightness difference and unevendisplay due to the size variation of the comb electrode 53.

SEVENTH EMBODIMENT

A liquid crystal display device according to a seventh embodiment of theinvention will be described with reference to FIG. 46. FIG. 46 is a planview showing a structure of one pixel of the liquid crystal displaydevice according to this embodiment. Incidentally, structural elementssimilar to those of the liquid crystal display device according to thefifth embodiment are denoted by the same reference numerals and theirdescription will be omitted or simplified.

The basic structure of the liquid crystal display device according tothis embodiment is almost the same as the liquid crystal display deviceaccording to the fifth embodiment except for the shape of an electrodeunit 60 constituting a pixel electrode 16. A main feature of the liquidcrystal display device according to this embodiment is that an electrodeunit 60 a is formed on a storage capacitor electrode 19.

As shown in FIG. 46, the pixel electrode 16 of the liquid crystaldisplay device according to this embodiment includes the electrode unit60 a which is formed at the center of the pixel area in which thestorage capacitor electrode 19 is formed, has the rectangular outerperiphery, and is smaller than the pixel area, and a plurality ofelectrode units 60 b which are formed between the electrode unit 60 aand upper and lower gate bus lines 12, and each of which has arectangular outer periphery and is smaller than the pixel area. Theelectrode units 60 a and 60 b are separated by a slit 62. Further, thepixel electrode 16 includes a connection electrode 64 for electricallyconnecting the electrode units 60 a and 60 b, separated by the slit 62,to each other. In FIG. 46, in the direction parallel to the drain busline 14, there are disposed the one electrode unit 60 a, and the two(four in total) electrode units 60 b disposed between the electrode unit60 a and the upper and lower gate bus line 12.

The electrode unit 60 a is electrically connected to the storagecapacitor electrode 19 through a contact hole formed in an insulatingfilm under the electrode unit 60 a.

The electrode unit 60 a includes a rectangular portion 96 having sidesalmost parallel to or vertical to the gate bus line 12 and the drain busline 14, and a solid part 46 having convex portions 97 protruding fromthe sides of the rectangular portion 96 parallel to a drain bus line 14and covering the upper sides of both ends of the storage capacitorelectrode 19.

Besides, the electrode unit 60 a includes a stem part 48 branching fromthe center of the side of the rectangular portion 96 of the solid part46 parallel to the gate bus line 12 and extending almost parallel to thedrain bus line 14, and the size of the stem part 48 is, for example, 5μm in length and 5 μm in width.

Further, the electrode unit 60 a includes a plurality of branch parts 49branching from the rectangular portion 96 of the solid part 46 and theconvex portion 97 and extending obliquely with respect to the stem part48 to form a comb shape, and electrode blank parts 66 between theadjacent branch parts 49. In an area partitioned by the adjacent stemparts 48 and the rectangular portion 96, the respective branch parts 49branching from the solid part 46 extend in almost the same direction.

On the other hand, the electrode unit 60 b includes a rectangular solidpart 46 having sides almost parallel to or vertical to the gate bus line12 and the drain bus line 14. The width of the rectangular solid part 46of the electrode unit 60 b in the direction parallel to the gate busline 12 is, for example, 60 μm. Besides, the width in the directionparallel to the drain bus line 14 is, for example, 39 μm.

Besides, the electrode unit 60 b includes a stem part 48 branching fromthe center of each of the sides of the solid part 46 and extendingalmost in parallel with or vertically to the gate bus line 12 and thedrain bus line 14. The size of the stem part 48 extending almost inparallel with the gate bus line 12 is, for example, 9 μm in length and 5μm in width. The size of the stem part 48 extending almost in parallelwith the drain bus line 14 is, for example, 5 μm in length and 5 μm inwidth.

Further, the electrode unit 60 b includes a plurality of branch parts 49branching from the solid part 46 and extending obliquely with respect tothe stem part 48 to form a comb shape, and electrode blank parts 66between the adjacent branch parts 49. In an area partitioned by theadjacent stem parts 48, the branch parts branching from the solid part46 and the stem parts 48.extend in almost the same direction.

An angle between the stem part 48 and the branch part 49 in theelectrode units 60 a and 60 b is, for example, 45°. The width of thebranch part 49 is, for example, 3 μm and the width of the branch part 66is, for example, 3 μm.

The ends of the respective branch parts 49 of the electrode units 60 aand 60 b are formed almost in parallel with or vertically to the gatebus line 12 and the drain bus line 14, and by this, the outerperipheries of the electrode units 60 a and 60 b are almost rectangular.The width of the outer periphery of the electrode unit 60 a in thedirection parallel to the gate bus line 12 is, for example, 78 μm, andthe width in the direction parallel to the drain bus line 14 is, forexample, 64 μm. The width of the outer periphery of the electrode unit60 b in the direction parallel to the gate bus line 12 is, for example,78 μm, and the width in the direction parallel to the drain bus line 14is, for example, 49 μm.

The adjacent electrode units 60 a and 60 b are electrically connected toeach other by the connection electrode 64 formed to be connected to thestem parts 48 positioned at the centers of the sides of the rectangularelectrode units 60 a and 60 b parallel to the gate bus line 12.

Besides, in the lower part of the pixel area in the drawing, a drainelectrode 36 of a TFT 20 of a lower adjacent pixel area is formed toprotrude. From the same reason as the case of the third embodiment, theshape of the electrode unit 60 b (lowermost one in FIG. 46)corresponding to this area is formed into such a shape that a part ofthe rectangle is cut away in conformity with the shape of the drainelectrode 36. Specifically, while the shape of the outer periphery ofthe other electrode unit 60 b is a rectangle of 49 μm×78 μm, the shapeof the outer periphery of the electrode unit 60 in this area is such ashape that a part of the rectangle is cut away so that it is spaced fromthe drain electrode 36 by 7 μm.

As stated above, the electrode unit 60 a constituting the pixelelectrode 16 may be formed on the storage capacitor electrode 19 formedin the vicinity of the center of the pixel area.

Although the shape of the electrode unit 60 a formed on the storagecapacitor electrode 19 is not limited to that shown in FIG. 46, it ispreferable that the shape satisfies following conditions.

First, it is necessary that the electrode unit 60 a includes the solidpart to cover all the area on the storage capacitor electrode 19.

Besides, in the area where the storage capacitor electrode 19 is formed,the same conductive layer as the gate bus line 12 and the drain bus line14 is formed in a laminate state through an insulating film. Thus, lightcan hardly pass through the area where the storage capacitor electrode19 is formed. Accordingly, it is necessary that the electrode unit 60 aincludes a solid part also in an area other than the area on the storagecapacitor electrode 19.

EIGHTH EMBODIMENT

A liquid crystal display device according to an eighth embodiment of theinvention and a method of manufacturing the same will be described withreference to FIGS. 47 to 55C. Incidentally, structural elements similarto those of the liquid crystal display device according to the fifthembodiment are denoted by the same reference numerals and theirdescription will be omitted or simplified.

First, the liquid crystal display device according to this embodimentwill be described with reference to FIGS. 47 to 53B. FIG. 47 is a planview showing a structure of one pixel of the liquid crystal displaydevice according to this embodiment, FIG. 48A is a sectional view takenalong line A–A′ of FIG. 47, FIG. 48B is a sectional view taken alongline B–B′, FIG. 49 is a view showing an arrangement of a polarizingplate and the like of the liquid crystal display device according tothis embodiment, FIG. 50 is a plan view showing a structure of one pixelin a case where the number of reflecting electrode layers is changed inthe liquid crystal display device according to this embodiment, FIG. 51is a plan view showing a structure of one pixel in a case where areflecting electrode is formed in an area where a storage capacitorelectrode is formed in the liquid crystal display device according tothis embodiment, FIGS. 52A and 52B are graphs showing a relation betweenthe opening rate of BM and the reflectivity in the liquid crystaldisplay device according to this embodiment and a relation between theopening rate of BM and the transmissivity, and FIGS. 53A and 53B aregraphs showing a relation between the areal ratio of a reflection areaand the reflectivity in the liquid crystal display device according tothis embodiment and a relation between the areal ratio of the reflectionarea and the transmissivity.

The liquid crystal display device according to this embodiment is theliquid crystal display device having functions of both the transmissiontype and the reflection type in which a reflecting electrode is furtherprovided at the TFT substrate 2 side in the liquid crystal displaydevice according to the fifth embodiment.

As shown in FIG. 47, a pixel electrode 16 similar to the liquid crystaldisplay device according to the fifth embodiment is formed in a pixelarea surrounded by a gate bus line 12 and a drain bus line 14.

A TFT 20 is formed in the vicinity of an intersection position betweenthe gate bus line 12 and the drain bus line 14 similarly to the liquidcrystal display device of the fifth embodiment. Here, a drain electrode36 and a source electrode 38 are made of a conductive film, for example,a lamination film of an aluminum film and a titanium film, and these areformed of the same conductive film. An area just under a channelprotective film of the gate bus line 12 functions as a gate electrode ofthe TFT 20.

Further, a reflecting electrode 55 having almost the same shape as asolid part 46 is formed under an electrode unit 60 to overlap with thesolid part 46 through an insulating film. The width of the reflectingfilm 55 in the direction parallel to the gate bus line 12 is, forexample, 60 μm. The width in the direction parallel to the drain busline 14 is, for example, 25 μm. Incidentally, the reflecting electrode55 has only to have the shape almost equal to or smaller than the solidpart 46 of the electrode unit 60 formed thereon.

The electrode unit 60 and the reflecting electrode 55 are electricallyconnected to each other through a contact hole 28. The contact hole 28is formed in a rectangular area of 15 μm×50 μm spaced inward from theouter periphery of the reflecting electrode 55 by, for example, 5 μm.

The reflecting electrode 55 is formed of, for example, the sameconductive film as the source electrode 38. Then, the reflectingelectrode 55 (upper one in FIG. 47) in the vicinity of the TFT 20 isformed integrally with the source electrode 38. By this, the pixelelectrode 16 is electrically connected to the source electrode 38.

FIGS. 48A and 48B show the sectional structure of the area where theelectrode unit 60 and the reflecting electrode 55 are formed. As shownin the drawings, the reflecting electrode 55 made of a lamination filmof, for example, an aluminum film 29 and a titanium film 31 is formed onan insulating film 22 formed on a glass substrate 10 on which the gatebus line 12 and the like are formed. An insulating film 25 is formed onthe insulating film 22 and the reflecting electrode 55. The contact hole28 reaching the aluminum film 29 is formed in the insulating film 25 andthe titanium film 31. The electrode unit 60 is formed on the insulatingfilm 25 in which the contact hole 28 is formed. The electrode unit 60 isformed so that the positions of the reflecting electrode 55 thereunderand the solid part 46 are aligned, and the center portion of the solidpart 46 is electrically connected to the aluminum film 29 of thereflecting electrode 55 through the contact hole 28. The electrode units60 formed on the reflecting electrodes 55 in this way are electricallyconnected to each other by the connection electrode 64 as shown in FIGS.47 and 48B.

FIG. 49 shows the arrangement of the polarizing plate and the like ofthe liquid crystal display device according to this embodiment. As shownin the drawing, in the liquid crystal display device according to thisembodiment, in addition to the arrangement of the polarizing plate ofthe liquid crystal display device according to the third embodimentshown in FIG. 35, an optical path control film 79 as an opticalscattering layer is disposed on a polarizing plate 86 at the observationside. The optical path control film 79 is the film for scattering lightin a specified direction.

In this way, the liquid crystal display device according to thisembodiment is constructed.

Next, the operation of the liquid crystal display device according tothis embodiment will be described.

In the state where a voltage is not applied between the pixel electrode16 and the opposite electrode 42, liquid crystal molecules are alignedalmost vertically to the substrate surface.

First, in the case where outside light is incident on the pixel area inthe state where a voltage is not applied between the pixel electrode 16and the opposite electrode 42, the light is reflected by the reflectingelectrode 55 formed in the reflection area. With respect to thereflected light, since the liquid crystal molecules are verticallyaligned, its polarization state is not changed, and the light isabsorbed by the polarizing plate 86 at the observer side. In this way, ablack display is realized.

Next, in the case where a backlight is turned on in the state where avoltage is not applied between the pixel electrode 16 and the oppositeelectrode 42, light from the backlight unit having been transmittedthrough the polarizing plate 87 formed on the back surface of the liquidcrystal panel is transmitted through a transparent area where thereflecting electrode 55 is not formed. Here, with respect to the lightfrom the backlight unit, since the liquid crystal molecules arevertically aligned, its polarization state is not changed, and the lightis absorbed by the polarizing plate 86 at the observer side. In thisway, a black display is realized.

On the other hand, when a voltage is applied between the pixel electrode16 and the opposite electrode 42, the liquid crystal molecules areobliquely aligned, cause birefringence as an optical effect, and changethe polarization state of the light.

In the case where the outside light is incident on the pixel area in thestate where the voltage is applied between the pixel electrode 16 andthe opposite electrode 42, with respect to the light reflected by thereflecting electrode, since its polarization state is changed, the lightis transmitted through the polarizing plate 86 at the observer side. Inthis way, a display from gray to white is realized.

Here, in the liquid crystal display device according to this embodiment,the film for scattering the light incident at a predetermined angle isused for the optical path control film 79 as the optical scatteringlayer. By this optical path control film 79, for example, incident lightfrom the sun is scattered similarly to the liquid crystal display devicedisclosed in non-patent document 1, and the light reflected by thereflecting electrode 55 and reaching the observer can be used for thedisplay. By this, even in the case of the light source such as the sun,the surface reflection is avoided, and the reflected light from thereflecting electrode 55 can be observed as the display.

Besides, in the case where the backlight is turned on in the state wherethe voltage is applied between the pixel electrode 16 and the oppositeelectrode 42, also with respect to the incident light from the backlightunit, its polarization state is changed and the light is transmittedthrough the polarizing plate 86 at the observer side. In this way, adisplay of gray to white is realized.

Incidentally, in the case where the backlight is turned on in thetransmission type, there is little influence on the display quality bythe reflection of the outside light. This is because both the blackdisplay in the transmission type and the black display in the reflectiontype are realized at the time of voltage non-application, and at thetime of the black display in the transmission type, there is noreflection from the outside light.

The liquid crystal display device according to this embodiment ischaracterized in that the reflecting electrode 55 is formed of the sameconductive film as the source electrode 38 formed on the TFT substrate2. By this, since the reflecting electrode 55 can also be simultaneouslyformed in the step of forming the source electrode 38, the liquidcrystal display device having the functions of both the reflection typeand the transmission type can be manufactured without increasing thenumber of steps of the manufacture process of the transmission typeliquid crystal display device.

Incidentally, in the case shown in FIG. 47, although the reflectingelectrode 55 is provided under all the electrode units 60 in one pixel,the reflecting electrode 55 may not be provided under all the electrodeunits 60. By changing the number of areas where the reflecting electrode55 is provided and the areas, the reflectivity and transmissivity of theliquid crystal panel can be changed.

For example, as shown in FIG. 50, the reflecting electrode 55 isprovided under the upper electrode unit 60 in the drawing with respectto the storage capacitor busline 18, and the reflecting electrode 55 maynot be provided under the lower electrode unit 60 in the drawing. Inthis case, as compared with the case where the reflecting electrode 55is provided under all the electrode units 60 of one pixel as shown inFIG., 47, since the number of the reflecting electrodes 55 is halved,the transmissivity of the liquid crystal panel is increased, and thereflectivity is decreased.

In order to effectively use an area in one pixel and to reduce the wasteof a reflection area and a transmission area, for example, it iseffective to form the reflecting electrode 55 under conditions as setforth below.

First, it is necessary to electrically connect the source electrode 38and the pixel electrode 16 without fail. Then, the reflecting electrode55 is formed under the electrode unit 60 directly electrically connectedto the source electrode 38.

Besides, in the case where the storage capacitor electrode 19 is formed,the area where the storage capacitor electrode 19 is formed can notbecome the area through which light is transmitted. Thus, the reflectingelectrode 55 is formed in the area where the storage capacitor electrode19 is formed.

By forming the reflecting electrode 55 to satisfy such conditions, thearea in one pixel can be effectively used.

FIG. 51 is a plan view showing the structure of one pixel in the casewhere the reflecting electrode 55 is formed in an area where the storagecapacitor electrode 19 is formed. In this case, for example, the pixelelectrode 16 is made the same as that of the liquid crystal displaydevice according to the seventh embodiment in which the electrode unit60 a is formed on the storage capacitor electrode 19. The reflectingelectrode 55 having almost the same shape as the solid part 46 is formedunder this electrode unit 60 a to overlap with the solid part 46 throughthe insulating film. The electrode unit 60 a and the reflectingelectrode 55 formed thereunder are electrically connected to each otherthrough the contact hole 28.

Besides, under the electrode unit 60 b in the vicinity of the upper TFT20 in FIG. 51, the reflecting electrode 55 having almost the same shapeas the solid part 46 is formed to overlap with the solid part 46 throughthe insulating film. The reflecting electrode 55 formed under theelectrode unit 60 b in the vicinity of the TFT 20 is formed integrallywith the source electrode 38. The electrode unit 60 b in the vicinity ofthe TFT 20 and the reflecting electrode 55 formed thereunder areelectrically connected to each other through the contact hole 28, and bythis, the electrode unit 60 b in the vicinity of the TFT 20 and thesource electrode 38 are electrically connected to each other.

The reflecting electrode 55 is not formed under the electrode unit 60 bbetween the electrode unit 60 b electrically connected to the sourceelectrode 38 through the contact hole 28 and the electrode unit 60 a onthe storage capacitor electrode 19. Besides, in the drawing, thereflecting electrode 55 is not formed under two electrode units 60 abelow the storage capacitor electrode bus line 18.

As described above, by changing the number of areas where the reflectingelectrode 55 is formed and the areas, the reflectivity andtransmissivity of the liquid crystal panel can be changed. That is,desired reflectivity and transmissivity can be set by suitably setting,in the pixel area, the areal ratio of the reflection area where thereflecting electrode 55 is formed in the pixel area and the areal ratioof the transmission area where the reflecting electrode 55 is notformed.

For example, in the area of the opening part 98 of the BM for shadingthe end part of the pixel area, the relations of the areal ratio of thereflection area with respect to the transmissivity and the reflectivitybecome as indicated by graphs shown in FIGS. 52A and 52B. FIG. 52A isthe graph showing the relation of the areal ratio of the reflection areawith respect to the reflectivity, and FIG. 52B is the graph showing therelation of the areal ratio of the reflection area with respect to thetransmissivity.

From the graphs shown in FIGS. 52A and 52B, it is understood that forexample, in order to obtain the reflectivity of 5% or more and thetransmissivity of 5% or more, the areal ratio of the reflection area inthe area of the opening part 98 of the BM for shading the end part ofthe pixel area has only to be set in a range of 10 to 25%.

Besides, the relations of the areal ratio of the transmission area inthe area of the opening part 98 of the BM for shading the end part ofthe pixel area with respect to the reflectivity and the transmissivitybecome as indicated by graphs shown in FIGS. 53A and 53B. FIG. 53A isthe graph showing the relation of the areal ratio of the transmissionarea with respect to the reflectivity, and FIG. 53B is the graph showingthe relation of the areal ratio of the transmission area with respect tothe transmissivity.

From the graphs shown in FIGS. 53A and 53B, it is understood that forexample, in order to obtain the reflectivity of 5% or more and thetransmissivity of 5% or more, the areal ratio of the transmission areain the area of the opening part 98 of the BM for shading the end of thepixel area has only to be set in a range of 50 to 90%.

Next, a method of manufacturing the liquid crystal display deviceaccording to this embodiment will be described with reference to FIGS.54A to 55C. FIGS. 54A to 55C are process sectional views showing themethod of manufacturing the liquid crystal display device according tothis embodiment, and correspond to the section in the direction alongthe drain bus line 14 of FIG. 47. Incidentally, in the following, adescription will be given to the method up to the formation of the pixelelectrode 16 on the glass substrate 10 of the TFT substrate 2.

First, similarly to the case of the third embodiment, a gate bus line 12and a storage capacitor bus line 18 are formed on the glass substrate10.

Next, an aluminum film 29 is formed by, for example, a sputter methodthrough a not-shown insulating film on the glass substrate 10 on whichthe gate bus line 12 and the like are formed (see FIG. 54A).

Next, a titanium film 31 is formed on the aluminum film 29 by, forexample, the sputtering method (see FIG. 54B).

Next, the titanium film 31 and the aluminum film 29 are patterned, sothat a reflecting electrode 55 is formed (see FIG. 54C). At this time, adrain bus line 14, a drain electrode 36, a source electrode 38 and astorage capacitor electrode 19 are formed at the same time. In this way,the reflecting electrode 55 is formed of the same conductive film as thedrain bus line 14, the drain electrode 36, the source electrode 38 andthe storage capacitor electrode 19.

Next, an insulating film 25 made of a silicon oxide film is formed onthe whole surface by, for example, a CVD method (see FIG. 54D).

Next, the insulating film 25 and the titanium film 31 are selectivelyetched, so that a contact hole 28 reaching the aluminum film 29 of thereflecting electrode 55 is formed (see FIG. 55A).

Next, a transparent conductive film 27 made of ITO is formed on thewhole surface by, for example, the sputtering method (see FIG. 55B).

Next, the transparent conductive film 27 is patterned, so that anelectrode unit 60, a connection electrode 64 and a contact area 67 areformed (see FIG. 55C). In this way, the pixel electrode 16 is formed onthe glass substrate 10 of the TFT substrate 2.

Then, although not shown, a process similar to a manufacture process ofa normal liquid crystal display device is performed subsequently tothis, so that the liquid crystal display device according to thisembodiment can be completed.

As stated above, according to this embodiment, since the reflectingelectrode 55 can be formed at the same time in the process of formingthe source electrode 38 and the like, the liquid crystal display devicehaving the functions of both the reflection type and the transmissiontype can be manufactured without increasing the number of steps of themanufacture process of the transmission type liquid crystal displaydevice.

NINTH EMBODIMENT

A liquid crystal display device according to a ninth embodiment of theinvention will be described with reference to FIGS. 56 to 57B. FIG. 56is a plan view showing a structure of one pixel of the liquid crystaldisplay device according to this embodiment, FIG. 57A is a sectionalview taken along line A–A′of FIG. 56, and FIG. 57B is a sectional viewtaken along line B–B′. Incidentally, structural elements similar tothose of the liquid crystal display device according to the eighthembodiment are denoted by the same reference numerals, and theirdescription will be omitted or simplified.

In the liquid crystal display device according to the eighth embodiment,the electrode units 60 constituting the pixel electrode 16 areelectrically connected to each other by the connection electrode 64formed in the same layer as an electrode unit 60.

A main feature of the liquid crystal display device according to thisembodiment is that a connection electrode 64 is not formed in the samelayer as an electrode unit 60, and a connection electrode 57 is formedin the same layer as a reflecting electrode 55, and the reflectingelectrodes 55 are electrically connected to each other. By this, theelectrode units 60 electrically connected to the reflecting electrodes55 through contact holes 28 are electrically connected to each other.

That is, as shown in FIG. 56, although the electrode unit 60 similar tothat of the liquid crystal display device according to the eighthembodiment shown in FIG. 47 is formed in the pixel area, the connectionelectrode 64 for electrically connecting these is not formed.

On the other hand, as shown in FIGS. 57A and 57B, the reflectingelectrode 55 made of a lamination film of an aluminum film 29 and atitanium film 31 is formed through an insulating film 25 under theelectrode unit 60. The insulating film is made of, for example, acrylresin, and its thickness is 2 μm. The electrode unit 60 is electricallyconnected to the aluminum film 29 of the reflecting electrode 55 throughthe contact hole 28.

Further, as shown in FIG. 57B, the reflecting electrodes 55 areelectrically connected to each other by the connection electrode 57 madeof the same layer as the aluminum film 29 of the reflecting electrode55. The insulating film 25 is formed on the connection electrode 57. Inthis way, the reflecting electrodes 55 are electrically connected toeach other through the connection electrode 57, so that the electrodeunits 60 electrically connected to the reflecting electrodes 55 throughthe contact holes 28 are electrically connected to each other.

In the liquid crystal display device according to this embodiment, theconnection electrode 57 for electrically connecting the electrode units60 to each other is covered with the insulating film 25 made of a thickresin or the like, and is not exposed at the liquid crystal side. Thus,the movement of a singular point due to the existence of the connectionelectrode 57 is suppressed. Accordingly, even if the protrudingstructure 73 is not provided at the CF substrate 4 side like the liquidcrystal display device according to the eighth embodiment, it becomespossible to stabilize the occurrence of the singular point. By this, aprocess of forming the protruding structure 73 on the CF substrate 4side can be omitted, and the liquid crystal display device can bemanufactured using the simpler manufacture process and at low cost.

TENTH EMBODIMENT

A liquid crystal display device according to a tenth embodiment of theinvention will be described with reference to FIG. 58. FIG. 58 is asectional view of the liquid crystal display device according to thisembodiment taken in a direction along a gate bus line. Incidentally,structural elements similar to those of the liquid crystal displaydevice according to the eighth embodiment are denoted by the samereference numerals and their description will be omitted or simplified.

The basic structure of the liquid crystal display device according tothis embodiment is almost the same as the liquid crystal display deviceaccording to the eighth embodiment. A main feature of the liquid crystaldisplay device according to this embodiment is that a bank-shapedstructure having almost the same size as a reflecting electrode 55 isformed at a CF substrate 4 side and at almost the same position as thereflecting electrode 55 formed on a TFT substrate 2.

That is, as shown in FIG. 58, a bank-shaped structure 69 having almostthe same size as the reflecting electrode 55 is formed on an oppositeelectrode 42 formed on a surface of the CF substrate 4 opposite to theTFT substrate 2 at almost the same position as the reflecting electrode55. The width of the bank-shaped structure 69 in the direction parallelto the gate bus line 12 is, for example, 60 μm. Besides, the width inthe direction parallel to the drain bus line 14 is, for example, 25 μm.The thickness of the bank-shaped structure 69 is almost half of a cellgap between the CF substrate 4 and the TFT substrate 2.

As stated above, in the liquid crystal display device according to thisembodiment, the bank-shaped structure 69 having almost the same size asthe reflecting electrode 55 is formed on the CF substrate 4 side atalmost the same position as the reflecting electrode 55 formed on theTFT substrate 2. By this bank-shaped structure 69, similarly to theliquid crystal display device according to the eighth embodiment inwhich the protruding structure 73 is formed.

Further, in the liquid crystal display device according to thisembodiment, by the bank-shaped structure 69, the thickness of the liquidcrystal layer in the reflection area is almost half of that in the otherarea. Thus, when light incident on the reflection area where thereflecting electrode 55 is formed is incident from the observer side, isreflected by the reflecting electrode 55, and is emitted toward theobserver side, the light is transmitted through the liquid crystalhaving almost the same thickness as the liquid crystal through whichlight from a backlight unit is transmitted in a transmission area wherethe reflecting electrode 55 is not formed. By this, coloring in thereflection area can be reduced.

MODIFIED EXAMPLE

A liquid crystal display device according to a modified example of thetenth embodiment of the invention will be described with reference toFIG. 59. FIG. 59 is a sectional view of the liquid crystal displaydevice according to this modified example taken in a direction along agate bus line.

In the liquid crystal display device according to this modified example,a protruding structure 73 is further provided on a bank-shaped structure69. The protruding structure 73 in the liquid crystal display deviceaccording to this modified example is similar to the protrudingstructure 73 in the liquid crystal display device according to the fifthembodiment, and is formed on the bank-shaped structure 69 so that it ispositioned almost at the center of the electrode unit 60.

As stated above, also by providing the bank-shaped structure 69 and theprotruding structure 73 on the CF substrate 4 side, and coloring in thereflection area can be reduced.

ELEVENTH EMBODIMENT

A liquid crystal display device according to an eleventh embodiment ofthe invention and a method of manufacturing the same will be describedwith reference to FIGS. 60 to 63C. Incidentally, structural elementssimilar to those of the liquid crystal display device according to theeighth embodiment are denoted by the same reference numerals and theirdescription will be omitted or simplified.

First, the liquid crystal display device according to this embodimentwill be described with reference to FIG. 60. FIG. 60 is a sectional viewof the liquid crystal display device according to this embodiment takenin a direction along a gate bus line.

The basic structure of the liquid crystal display device according tothis embodiment is almost the same as the liquid crystal display deviceaccording to the eighth embodiment. In the liquid crystal display deviceaccording to this embodiment, a bank-shaped structure 65 having almostthe same size as a reflecting electrode 55 and having a plane shape isformed under the reflecting electrode 55. That is, a main feature isthat the reflecting electrode 55 and an electrode unit 60 are formed onan upper surface and a side surface of the bank-shaped structure 65formed at a TFT substrate 2 side.

As shown in FIG. 60, the bank-shaped structure 65 is formed on aninsulating film 22 formed on a glass substrate 10 on which a gate busline 12 and the like are formed. The reflecting electrode 55 made of alamination film of an aluminum film 29 and a titanium film 31 is formedin an area including the upper surface and the side surface of thebank-shaped structure 65. The electrode unit 60 is formed on thereflecting electrode 55 through an insulating film 25. The electrodeunit 60 is electrically connected to the aluminum film 29 of thereflecting electrode 55 through a contact hole 28 at the upper surfaceof the bank-shaped structure 65.

As stated above, in the liquid crystal display device according to thisembodiment, the bank-shaped structure 65 having almost the same size asthe reflecting electrode 55 is formed under the reflecting electrode 55.By this bank-shaped structure 65, similarly to the liquid crystaldisplay device according to the tenth embodiment in which thebank-shaped structure 69 is formed at the CF substrate 4 side.

Further, in the liquid crystal display device according to thisembodiment, similarly to the liquid crystal display device according tothe tenth embodiment, since the thickness of the liquid crystal layer inthe reflection area where the reflecting electrode 55 is formed, isalmost half of that in the other area by the bank-shaped structure 65,coloring in the reflection area can be reduced.

Next, a method of manufacturing the liquid crystal display deviceaccording to this embodiment will be described with reference to FIGS.61A to 63C. FIGS. 61A to 63C are process sectional views showing themethod of manufacturing the liquid crystal display device according tothis embodiment. Incidentally, in the following, a description will begiven to the method up to the formation of the pixel electrode 16 on theglass substrate 10 of the TFT substrate 2.

First, similarly to the case of the third embodiment, a gate bus line 12and a storage capacitor bus line 18 are formed on the glass substrate10.

Next, a resin layer 32 made of acryl resin, novolac resin or the like isformed on the glass substrate 10 on which the gate bus line 12 and thelike are formed through a not-shown insulating film (see FIG. 61A).

Next, the resin layer 32 is patterned, so that a bank-shaped structure65 is formed (see FIG. 61B).

Next, an aluminum film 29 is formed on the whole surface by, forexample, a sputtering method (see FIG. 61C).

Next, a titanium film 31 is formed on the aluminum film 29 by, forexample, the sputtering method (see FIG. 62A).

Next, the titanium film 31 and the aluminum film 29 are patterned, sothat a reflecting electrode 55 is formed on an upper surface and a sidesurface of the bank-shaped structure 65 (see FIG. 62B). At this time, adrain bus line 14, a drain electrode 36, a source electrode 38 and astorage capacitor electrode 19 are formed at the same time. In this way,the reflecting electrode 55 is formed of the same conductive film as thedrain bus line 14, the drain electrode 36, the source electrode 38 andthe storage capacitor electrode 19.

Next, an insulating film 25 made of a silicon oxide film is formed onthe whole surface by, for example, a CVD method (see FIG. 62C).

Next, the insulating film 25 and the titanium film 31 are selectivelyetched, so that a contact hole 28 reaching the aluminum film 29 of thereflecting electrode 55 is formed (see FIG. 63A).

Next, a transparent conductive film 27 made of ITO is formed on thewhole surface by, for example, the sputtering method (see FIG. 63B).

Next, the transparent conductive film 27 is patterned, so that anelectrode unit 60, a connection electrode 64 and a contact area 67 areformed (see FIG. 63C). In this way, the pixel electrode 16 is formed onthe glass substrate 10 of the TFT substrate 2.

Then, although not shown, subsequently to this, a similar process to amanufacture process of a normal liquid crystal display device isperformed, so that the liquid crystal display device according to thisembodiment can be completed.

MODIFIED EXAMPLE

A liquid crystal display device according to a modified example of theeleventh embodiment of the invention will be described with reference toFIG. 64. FIG. 64 is a sectional view of the liquid crystal displaydevice according to this modified example taken in a direction along agate bus line.

In the liquid crystal display device according to this modified example,as shown in FIG. 64, similarly to the liquid crystal display deviceaccording to the fifth embodiment, a protruding structure 73 is providedon an opposite electrode 42 formed on a surface of a CF substrate 4opposite to a TFT substrate 2.

TWELFTH EMBODIMENT

A liquid crystal display device according to a twelfth embodiment of theinvention and a method of manufacturing the same will be described withreference to FIGS. 65 to 68C. Incidentally, structural elements similarto those of the liquid crystal display device according to the eighthembodiment are denoted by the same reference numerals and theirdescription will be omitted or simplified.

First, the liquid crystal display device according to this embodimentwill be described with reference to FIGS. 65 and 66. FIG. 65 is a planview showing a structure of one pixel of the liquid crystal displaydevice according to this embodiment, and FIG. 66 is a sectional viewtaken along line B–B′ of FIG. 65.

The basic structure of the liquid crystal display device according tothis embodiment is almost the same as the liquid crystal display deviceaccording to the eighth embodiment except for an area where reflectingelectrodes 55 are formed.

In the liquid crystal display device according to this embodiment, asshown in FIG. 65, the reflecting electrodes 55 are formed in an areawhere a slit 62 between electrode units 60 is formed. Similarly to theliquid crystal display device according to the eighth embodiment, thereflecting electrodes 55 are made of the same conductive film as asource electrode 38.

The width of the reflecting electrode 55 is slightly smaller than thewidth of the slit 62 so that the electrode unit 60 does not overlap withthe reflecting electrode 55 preferably. For example, the width of theslit 62 is 8 μm, and the width of the reflecting electrode 55 is 6 μm.

On the other hand, the reflecting electrode 55 is not formed under aconnection electrode 64 formed in the same layer as the electrode unit60 and for electrically connecting the electrode units 60.

As shown in FIG. 66, the reflecting electrodes 55 are formed on aninsulating film 22 formed on a glass substrate 10 on which a gate busline 12 and the like are formed. An insulating film 25 is formed on thereflecting electrodes 55 and the insulating film 22, and the electrodeunit 60 is formed on the insulating film 25.

The reflecting electrodes 55 in the area where the slit 62 is formed areelectrically separated from each other, and are in an electricallyfloating state.

A main feature of the liquid crystal display device according to thisembodiment is that the reflecting electrodes 55 are formed in the areawhere the slit 62 between the electrode units 60 is formed, and thereflecting electrodes 55 are not electrically connected to each other,but are in the floating state where they are electrically separated.

By forming the reflecting electrodes 55 as stated above, differentlyfrom an applied voltage in a transmission area where the electrode unit60 is formed, an effective voltage applied to liquid crystal moleculeson the reflecting electrodes 55 is caused from only electric fieldaround the electrode unit 60. Thus, the voltage applied to the liquidcrystal molecules on the reflecting electrodes 55 becomes low.Accordingly, the optical effect due to the liquid crystal is suppressedin the reflection area, and even in the case where the thickness of theliquid crystal layer in the reflection area is made the same as thethickness in the transmission area, coloring in the reflection area canbe reduced.

Next, a method of manufacturing the liquid crystal display deviceaccording to this embodiment will be described with reference to FIGS.67A to 68C. FIGS. 67A to 68C are process sectional views showing themethod of manufacturing the liquid crystal display device according tothis embodiment, and correspond to the section in the direction alongthe drain bus line 14 of FIG. 65. Incidentally, in the following, adescription will be given to the method up to the formation of the pixelelectrode 16 on the glass substrate 10 of the TFT substrate 2.

First, similarly to the case of the third embodiment, a gate bus line 12and a storage capacitor bus line 18 are formed on the glass substrate10.

Next, an aluminum film 29 is formed on the glass substrate 10 on whichthe gate bus line 12 and the like are formed though a not-showninsulating film by, for example, a sputtering method (see FIG. 67A).

Next, a titanium film 31 is formed on the aluminum film 29 by, forexample, the sputtering method (see FIG. 67B).

Next, the titanium film 31 and the aluminum film 29 are patterned, sothat a reflecting electrode 55 is formed (see FIG. 67C). At this time, adrain bus line 14, a drain electrode 36, a source electrode 38 and astorage capacitor electrode 19 are formed at the same time. In this way,the reflecting electrode 55 is formed of the same conductive film as thedrain bus line 14, the drain electrode 36, the source electrode 38 andthe storage capacitor electrode 19.

Next, an insulating film 25 made of a silicon oxide film is formed onthe whole surface by, for example, a CVD method (see FIG. 67D).

Next, the insulating film 25 and the titanium film 31 are patterned sothat an opening part 33 reaching the aluminum film 29 of the reflectingelectrode 55 is formed (see FIG. 68A).

Next, a transparent conductive film 27 made of ITO is formed on thewhole surface by, for example, the sputtering method (see FIG. 68B).

Next, the transparent conductive film 27 is patterned, so that anelectrode unit 60, a connection electrode 64 and a contact area 67 areformed (see FIG. 68C). In this way, the pixel electrode 16 is formed onthe glass substrate 10 of the TFT substrate 2.

Although not shown, subsequently to this, a process similar to amanufacture process of a normal liquid crystal display device isperformed so that the liquid crystal display device according to thisembodiment can be completed.

THIRTEENTH EMBODIMENT

A liquid crystal display device according to a thirteenth embodiment ofthe invention will be described with reference to FIGS. 69 and 70. FIG.69 is a plan view showing a structure of one pixel of the liquid crystaldisplay device according to this embodiment, and FIG. 70 is a sectionalview taken along line A–A′ of FIG. 69. Incidentally, structural elementssimilar to those of the liquid crystal display device according to thethird and the eighth embodiments are denoted by the same referencenumerals, and their description will be omitted or simplified.

The liquid crystal display device according to this embodiment includesa pixel electrode 16 similar to the liquid crystal display deviceaccording to the third embodiment, and a reflecting electrode 55 isformed in an area where a slit 62 is formed between electrode units 60constituting the pixel electrode 16 similarly to the liquid crystaldisplay device according to the twelfth embodiment.

That is, as shown in FIGS. 69 and 70, the reflecting electrode 55 isformed in the area where the slit 62 between the plurality of electrodeunits 60 disposed in the direction parallel to a gate bus line 12 andthe direction parallel to a drain bus line 14 is formed.

In the liquid crystal display device according to this embodiment, ascompared with the liquid crystal display device according to the twelfthembodiment, since the area of the slit 62 formed between the electrodeunits 60 is large, the square measure of the reflecting electrode 55 isalso large.

FOURTEENTH EMBODIMENT

A liquid crystal display device according to a fourteenth embodiment ofthe invention will be described with reference to FIGS. 71 and 72. FIG.71 is a plan view showing a structure of one pixel of the liquid crystaldisplay device according to this embodiment, and FIG. 72 is a sectionalview taken along line A–A′ of FIG. 71. Incidentally, structural elementssimilar to those of the liquid crystal display device according to thetwelfth embodiment are denoted by the same reference numerals and theirdescription will be omitted or simplified.

The basic structure of the liquid crystal display device according tothis embodiment is almost the same as the liquid crystal display deviceaccording to the twelfth embodiment. In the liquid crystal displaydevice according to this embodiment, as shown in FIG. 71, as comparedwith the liquid crystal display device according to the twelfthembodiment, an electrode unit 60 is formed to be small. For example, thewidth of the outer periphery of the electrode unit 60 in the directionparallel to the gate bus line 12 is, for example, 66 μm. Besides, thewidth in the direction parallel to the drain bus line 14 is, forexample, 33 μm.

Since the electrode unit 60 is formed to be small as stated above, theelectrode unit 60 is not formed in an area 99 having a predeterminedwidth from a side, parallel to a drain bus line 14, of an opening part98 of a BM for shading an end part of a pixel area. For example, theelectrode unit 60 is not formed in the area 99 having a width of 6 μmfrom the side, parallel to the drain bus line 14, of the opening part 98of the BM.

As shown in FIGS. 71 and 72, in the liquid crystal display deviceaccording to this embodiment, the reflecting electrode 55 is formed innot only the area where the slit 62 between the electrode units 60 isformed, but also the area 99 having the predetermined width from theside, parallel to the drain bus line 14, of the opening part 98 of theBM, where the electrode unit 60 is not formed.

As stated above, also by forming the reflecting electrode 55 in the areaaround the electrode unit 60, similarly to the liquid crystal displaydevice according to the twelfth embodiment, the effective voltageapplied to the liquid crystal molecules on the reflecting electrode 55is caused by only the electric field around the electrode unit 60. Thus,the voltage applied to the liquid crystal molecules on the reflectingelectrode 55 becomes small. By this, the optical effect due to theliquid crystal is suppressed in the reflection area, and coloring in thereflection area can be reduced.

As described above, according to the third to the fourteenthembodiments, the pixel electrode 16 includes the plurality of electrodeunits 60 disposed through the slit and electrically connected to eachother, and each of the electrode units 60 includes the solid part 46 andthe plurality of extension parts extending in the outer peripheraldirection of the electrode unit 60 from the solid part 46, so that theoccurrence of brightness difference due to the variation of width of theextension parts is suppressed, the uneven display can be reduced, andthe excellent display quality can be obtained.

Besides, according to the eighth to the fourteenth embodiments, sincethe reflecting electrode 55 is formed by patterning the same conductivefilm as the bus lines 12, 14 and 18 formed on the substrate or theelectrode of the TFT 20, the liquid crystal display device having thefunctions of both the reflection type and the transmission type can bemanufactured at low cost without increasing the number of steps of themanufacture process of the transmission type liquid crystal displaydevice.

Besides, according to the tenth and the eleventh embodiments, in thereflection area where the reflecting electrode 55 is formed, since thethickness of the liquid crystal layer is thinner than that in the otherarea, coloring in the reflection area can be reduced.

MODIFIED EMBODIMENT

The invention is not limited to the above embodiments, but can bevariously modified.

For example, in the above embodiments, although the description has beengiven to the case where the end parts of the respective branch parts 49of the electrode unit 60 are formed almost in parallel with orvertically to the gate bus line 12 and the drain bus line 14, and theouter periphery of the electrode unit 60 is almost square orrectangular, the shape of the end parts of the respective branch parts49 are not limited to these. For example, as shown in FIG. 73A, the endpart of the branch part 49 may be formed to be vertical to the extensiondirection. Besides, as shown in FIG. 73B, the branch part 49 may be madeto have such a shape that the width becomes gradually thin from the rootpart connected to the solid part 46 or the stem part 48 to the tip part.

Besides, in the above embodiments, although the description has beengiven to the case where the branch part 49 extends obliquely so that theangle between the stem part 48 and the branch part 49, in other words,the angle between the side of the outer periphery of the electrode unit60 and the branch part 49 becomes 45°, the extension direction of thebranch part 49 is not limited to the case as stated above. The extensiondirection of the branch part 49 has only to have an angle of 0 to 90°with respect to one side of the outer periphery of the electrode unit60. Similarly, although the description has been given to the case wherethe side of the outer periphery of the electrode unit 60 and the stempart 48 is 90°, the extension direction of the stem part 48 has only tohave an angle of 0 to 90° with respect to one side of the outerperiphery of the electrode unit 60. That is, the extension direction ofthe comb electrode 53 has only to have an angle of 0 to 90° with respectto one side of the outer periphery of the electrode unit 60.

Besides, in the above embodiments, although the description has beengiven to the case where the electrode units 60 having almost the sameshape are disposed in the pixel area, a plurality of electrode units 60different from each other in shape may be combined and disposed.

Besides, in the above embodiments, although the description has beengiven to the case of the electrode unit 60 having the square orrectangular outer periphery, the shape of the outer periphery of theelectrode unit 60 is not limited to these. For example, the shape of theouter periphery of the electrode unit 60 may be a convex polygon, and atthis time, the solid part 46 may have the side almost parallel to theside of the outer periphery of the electrode unit 60.

Besides, in the above embodiments, although the description has beengiven to the case where the number of the electrode units 60 in onepixel is 12, 6 or 5, the number of the electrode units 60 in one pixelis not limited to these. A predetermined number of electrode units 60can be suitably formed in accordance with the size of the pixel area.

Besides, in the above embodiment, although the description has beengiven to the case where the pixel electrode 16 is made the transparentelectrode made of ITO, the material of the pixel electrode 16 is notlimited to ITO. Besides, in the third to the seventh embodiments, thepixel electrode 16 may be formed of a conductive film having opticalreflectivity such as aluminum, and the reflection type liquid crystaldisplay device may be constructed.

Besides, in the above embodiments, although the description has beengiven to the case where the TFT 20 is formed as an active element fordriving the liquid crystal layer 6, the active element is not limited tothe TFT 20. For example, an MIM (Metal Insulator Metal) transistor orthe like may be used as the active element. Here, in the case where thereflecting electrode 55 is formed as in the case of the eighth to thefourteenth embodiments, the reflecting electrode 55 may be formed by thesame conductive film as the electrode of the active element.

Besides, in the above embodiments, although the description has beengiven to the liquid crystal display device where the CF is formed on theCF substrate 4 disposed to be opposite to the TFT substrate 2, theinvention is not limited to this, but can be applied to a so-calledCF-on-TFT structure liquid crystal display device in which the CF isformed on the TFT substrate 2.

Besides, in the eighth to the fourteenth embodiments, although thedescription has been given to the case where the reflecting electrode 55is formed of the same conductive film as the source electrode 38 or thelike, the conductive film forming the reflecting electrode 55 is notlimited to this. The reflecting electrode 55 may be formed of the sameconductive film as any one of the gate bus line 12, the drain bus line14, the drain electrode 36 of the TFT 20 and the source electrode 38thereof. Besides, the reflecting electrode 55 may be formed of aconductive film different from these.

Besides, in the eighth to the fourteenth embodiments, although thedescription has been given to the case where the shape of the electrodeunit 60 is similar to that of any one of the liquid crystal displaydevices according to the third to the seventh embodiments, the shape ofthe electrode unit 60 is not limited to these.

Besides, in the tenth and the eleventh embodiments, by providing thebank-shaped structures 69 and 65, in the reflection area where thereflecting electrode 55 is formed, the thickness of the liquid crystallayer is made thinner than that in the other area, however, the shape ofthe structure for thinning the liquid crystal layer is not limited tothe bank shape.

As described above, according to the present invention, it is possibleto realize the liquid crystal display device which can obtain excellentdisplay characteristics without raising manufacture cost.

1. A liquid crystal display device comprising: a first substrateincluding a plurality of gate bus lines disposed almost in parallel witheach other, a plurality of drain bus lines disposed almost in parallelwith each other to intersect with the gate bus lines, a plurality ofswitching elements respectively provided at intersection parts of thegate bus lines and the drain bus lines, and a plurality of pixelelectrodes formed and connected to the plurality of switching elements,respectively; a second substrate provided to be opposite to the firstsubstrate and having an opposite electrode opposite to the plurality ofpixel electrodes; and a liquid crystal layer sealed between the firstsubstrate and the second substrate and having a negative dielectricanisotropy, wherein each of the pixel electrodes includes a plurality ofelectrode units disposed through a slit and electrically connected toeach other, each of the electrode units includes a solid part and aplurality of extension parts extending from the solid part toward anouter peripheral direction of the electrode unit, and a ratio of asquare measure of the solid part to a square measure of an area withinan outer periphery of the electrode unit is 50% or more.
 2. A liquidcrystal display device according to claim 1, wherein the plurality ofelectrode unit are formed of a same conductive film.
 3. A liquid crystaldisplay device according to claim 1, wherein at least part of theplurality of extension parts are almost parallel to each other.
 4. Aliquid crystal display device according to claim 1, wherein theplurality of extension parts extend radially from a starting point of acenter part of the electrode unit to an outer periphery of the electrodeunit.
 5. A liquid crystal display device according to claim 1, whereinan extension direction of the extension part has an angle of 0 to 90°with respect to one side of an outer periphery of the electrode unit. 6.A liquid crystal display device according to claim 1, wherein the solidpart is positioned almost at a center of the electrode unit.
 7. A liquidcrystal display device according to claim 6, wherein a shape of thesolid part is a convex polygon.
 8. A liquid crystal display deviceaccording to claim 7, wherein the electrode unit includes a convexpolygonal outer periphery, and the solid part includes a side almostparallel to a side of the outer periphery of the electrode unit.
 9. Aliquid crystal display device according to claim 1, wherein the solidpart is continuously formed between two opposite sides of an outerperiphery of the electrode unit, and the plurality of extension partsare formed in an area at a side of an outer periphery of the electrodeunit where the solid part is not formed.
 10. A liquid crystal displaydevice according to claim 9, wherein a facing direction of the twoopposite sides is almost parallel to the gate bus lines or the drain buslines.
 11. A liquid crystal display device according to claim 1, whereinthe plurality of extension parts are formed in area at one side of anouter periphery of the electrode unit, and the solid part is formed inan area where the plurality of extension parts of the electrode unit arenot formed.
 12. A liquid crystal display device according to claim 11,wherein the plurality of extension parts are formed in an area at a sideof an outer periphery of the electrode unit opposite to the gate buslines or the drain bus lines.
 13. A liquid crystal display deviceaccording to claim 1, wherein four areas are defined in the electrodeunit, the plurality of extension parts are formed in at least one of thefour areas, and the solid part is formed in the other areas.
 14. Aliquid crystal display device according to claim 13, wherein theplurality of extension parts are formed in one pair of areas positioneddiagonally among the four areas, and the solid part is formed in theother pair of areas positioned diagonally.
 15. A liquid crystal displaydevice according to claim 1, wherein in the electrode unit, four areasare defined by diagonal lines of an outer periphery of the electrodeunit, the plurality of extension parts are disposed in at least one ofthe four areas, and the solid part is formed in the other areas.
 16. Aliquid crystal display device according to claim 15, wherein theplurality of extension parts are formed in one pair of areas positioneddiagonally among the four areas, the solid part is formed in the otherpair of areas positioned diagonally, and the one pair of areas are areasincluding a side of the outer periphery of the electrode unit at a sideof the drain bus line.
 17. A liquid crystal display device according toclaim 1, wherein the extension parts are formed in an area extendinginward from an outer periphery of the electrode unit by 5 μm or more.